Merge branch 'develop' into PlaybackContainer

.editorconfig

@@ -23,4 +23,4 @@ indent_size = 4
 trim_trailing_whitespace = true
 
 [*.{yml,yaml}]
-indent_size = 2
+indent_size = 4

.github/workflows/cypress.yaml

@@ -5,6 +5,9 @@ on:
         workflows: ["Element Web - Build"]
         types:
             - completed
+concurrency:
+    group: ${{ github.workflow }}-${{ github.event.workflow_run.head_branch || github.ref }}
+    cancel-in-progress: ${{ github.event.workflow_run.event == 'pull_request' }}
 jobs:
     prepare:
         name: Prepare
@@ -162,8 +165,9 @@ jobs:
                   PERCY_BRANCH: ${{ github.event.workflow_run.head_branch }}
                   PERCY_COMMIT: ${{ github.event.workflow_run.head_sha }}
                   PERCY_PULL_REQUEST: ${{ needs.prepare.outputs.pr_id }}
-                  PERCY_PARALLEL_TOTAL: ${{ strategy.job-total }}
                   PERCY_PARALLEL_NONCE: ${{ needs.prepare.outputs.uuid }}
+                  # We manually finalize the build in the report stage
+                  PERCY_PARALLEL_TOTAL: -1
 
             - name: Upload Artifact
               if: failure()
@@ -181,14 +185,35 @@ jobs:
               with:
                   name: cypress-junit
                   path: cypress/results
+
     report:
         name: Report results
-        needs: tests
+        needs:
+            - prepare
+            - tests
         runs-on: ubuntu-latest
         if: always()
         permissions:
             statuses: write
         steps:
+            - name: Finalize Percy
+              if: needs.prepare.outputs.percy_enable == '1'
+              run: npx -p @percy/cli percy build:finalize
+              env:
+                  PERCY_TOKEN: ${{ secrets.PERCY_TOKEN }}
+                  PERCY_PARALLEL_NONCE: ${{ needs.prepare.outputs.uuid }}
+
+            - name: Skip Percy required check
+              if: needs.prepare.outputs.percy_enable != '1'
+              uses: Sibz/github-status-action@v1
+              with:
+                  authToken: ${{ secrets.GITHUB_TOKEN }}
+                  state: success
+                  description: Percy skipped
+                  context: percy/matrix-react-sdk
+                  sha: ${{ github.event.workflow_run.head_sha }}
+                  target_url: https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}
+
             - uses: Sibz/github-status-action@v1
               with:
                   authToken: ${{ secrets.GITHUB_TOKEN }}
@@ -196,6 +221,7 @@ jobs:
                   context: ${{ github.workflow }} / cypress (${{ github.event.workflow_run.event }} => ${{ github.event_name }})
                   sha: ${{ github.event.workflow_run.head_sha }}
                   target_url: https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}
+
     testrail:
         name: Report results to testrail
         needs:

.github/workflows/pull_request.yaml

@@ -6,7 +6,5 @@ concurrency: ${{ github.workflow }}-${{ github.event.pull_request.head.ref }}
 jobs:
     action:
         uses: matrix-org/matrix-js-sdk/.github/workflows/pull_request.yaml@develop
-        with:
-            labels: "T-Defect,T-Enhancement,T-Task"
         secrets:
             ELEMENT_BOT_TOKEN: ${{ secrets.ELEMENT_BOT_TOKEN }}

.github/workflows/tests.yml

@@ -7,6 +7,10 @@ on:
         types: [upstream-sdk-notify]
     workflow_call:
         inputs:
+            disable_coverage:
+                type: boolean
+                required: false
+                description: "Specify true to skip generating and uploading coverage for tests"
             matrix-js-sdk-sha:
                 type: string
                 required: false
@@ -39,16 +43,21 @@ jobs:
               id: cpu-cores
               uses: SimenB/github-actions-cpu-cores@v1
 
-            - name: Run tests with coverage and metrics
+            - name: Load metrics reporter
+              id: metrics
               if: github.ref == 'refs/heads/develop'
-              run: "yarn coverage --ci --reporters github-actions '--reporters=<rootDir>/test/slowReporter.js' --max-workers ${{ steps.cpu-cores.outputs.count }}"
+              run: |
+                  echo "extra-reporter='--reporters=<rootDir>/test/slowReporter.js'" >> $GITHUB_OUTPUT
 
-            - name: Run tests with coverage
+            - name: Run tests
-              if: github.ref != 'refs/heads/develop'
+              run: |
-              run: "yarn coverage --ci --reporters github-actions --max-workers ${{ steps.cpu-cores.outputs.count }}"
+                  yarn ${{ inputs.disable_coverage != 'true' && 'coverage' || 'test' }} \
+                      --ci \
+                      --reporters github-actions ${{ steps.metrics.outputs.extra-reporter }} \
+                      --max-workers ${{ steps.cpu-cores.outputs.count }}
 
             - name: Upload Artifact
-              if: inputs.matrix-js-sdk-sha == ''
+              if: inputs.disable_coverage != 'true'
               uses: actions/upload-artifact@v3
               with:
                   name: coverage

cypress/e2e/crypto/decryption-failure.spec.ts

@@ -118,7 +118,12 @@ describe("Decryption Failure Bar", () => {
                         "Verify this device to access all messages",
                     );
 
-                    cy.percySnapshot("DecryptionFailureBar prompts user to verify");
+                    cy.get(".mx_DecryptionFailureBar").percySnapshotElement(
+                        "DecryptionFailureBar prompts user to verify",
+                        {
+                            widths: [320, 640],
+                        },
+                    );
 
                     cy.contains(".mx_DecryptionFailureBar_button", "Resend key requests").should("not.exist");
                     cy.contains(".mx_DecryptionFailureBar_button", "Verify").click();
@@ -146,8 +151,11 @@ describe("Decryption Failure Bar", () => {
                 "Open another device to load encrypted messages",
             );
 
-            cy.percySnapshot(
+            cy.get(".mx_DecryptionFailureBar").percySnapshotElement(
                 "DecryptionFailureBar prompts user to open another device, with Resend Key Requests button",
+                {
+                    widths: [320, 640],
+                },
             );
 
             cy.intercept("/_matrix/client/r0/sendToDevice/m.room_key_request/*").as("keyRequest");
@@ -155,8 +163,11 @@ describe("Decryption Failure Bar", () => {
             cy.wait("@keyRequest");
             cy.contains(".mx_DecryptionFailureBar_button", "Resend key requests").should("not.exist");
 
-            cy.percySnapshot(
+            cy.get(".mx_DecryptionFailureBar").percySnapshotElement(
                 "DecryptionFailureBar prompts user to open another device, " + "without Resend Key Requests button",
+                {
+                    widths: [320, 640],
+                },
             );
         },
     );
@@ -177,7 +188,9 @@ describe("Decryption Failure Bar", () => {
                 "Reset your keys to prevent future decryption errors",
             );
 
-            cy.percySnapshot("DecryptionFailureBar prompts user to reset keys");
+            cy.get(".mx_DecryptionFailureBar").percySnapshotElement("DecryptionFailureBar prompts user to reset keys", {
+                widths: [320, 640],
+            });
 
             cy.contains(".mx_DecryptionFailureBar_button", "Reset").click();
 
@@ -196,7 +209,12 @@ describe("Decryption Failure Bar", () => {
                 "Some messages could not be decrypted",
             );
 
-            cy.percySnapshot("DecryptionFailureBar displays general message with no call to action");
+            cy.get(".mx_DecryptionFailureBar").percySnapshotElement(
+                "DecryptionFailureBar displays general message with no call to action",
+                {
+                    widths: [320, 640],
+                },
+            );
         },
     );
 
@@ -210,7 +228,10 @@ describe("Decryption Failure Bar", () => {
         cy.get(".mx_DecryptionFailureBar").should("exist");
         cy.get(".mx_DecryptionFailureBar .mx_Spinner").should("exist");
 
-        cy.percySnapshot("DecryptionFailureBar displays loading spinner");
+        cy.get(".mx_DecryptionFailureBar").percySnapshotElement("DecryptionFailureBar displays loading spinner", {
+            allowSpinners: true,
+            widths: [320, 640],
+        });
 
         cy.wait(5000);
         cy.get(".mx_DecryptionFailureBar .mx_Spinner").should("not.exist");

cypress/e2e/location/location.spec.ts

@@ -27,7 +27,7 @@ describe("Location sharing", () => {
     };
 
     const submitShareLocation = (): void => {
-        cy.get('[data-test-id="location-picker-submit-button"]').click();
+        cy.get('[data-testid="location-picker-submit-button"]').click();
     };
 
     beforeEach(() => {

cypress/e2e/timeline/timeline.spec.ts

@@ -159,8 +159,8 @@ describe("Timeline", () => {
                     ".mx_GenericEventListSummary_summary",
                 "created and configured the room.",
             ).should("exist");
-            cy.get(".mx_Spinner").should("not.exist");
+
-            cy.percySnapshot("Configured room on IRC layout");
+            cy.get(".mx_MainSplit").percySnapshotElement("Configured room on IRC layout");
         });
 
         it("should add inline start margin to an event line on IRC layout", () => {
@@ -185,11 +185,12 @@ describe("Timeline", () => {
                 .should("have.css", "margin-inline-start", "104px")
                 .should("have.css", "inset-inline-start", "0px");
 
-            cy.get(".mx_Spinner").should("not.exist");
             // Exclude timestamp from snapshot
             const percyCSS =
-                ".mx_RoomView_body .mx_EventTile_info .mx_MessageTimestamp " + "{ visibility: hidden !important; }";
+                ".mx_RoomView_body .mx_EventTile_info .mx_MessageTimestamp { visibility: hidden !important; }";
-            cy.percySnapshot("Event line with inline start margin on IRC layout", { percyCSS });
+            cy.get(".mx_MainSplit").percySnapshotElement("Event line with inline start margin on IRC layout", {
+                percyCSS,
+            });
             cy.checkA11y();
         });
 
@@ -213,8 +214,7 @@ describe("Timeline", () => {
             cy.get(".mx_RoomView_body .mx_EventTile_info .mx_MessageTimestamp").click();
 
             // Exclude timestamp from snapshot
-            const percyCSS =
+            const percyCSS = ".mx_RoomView_body .mx_EventTile .mx_MessageTimestamp { visibility: hidden !important; }";
-                ".mx_RoomView_body .mx_EventTile .mx_MessageTimestamp " + "{ visibility: hidden !important; }";
 
             // should not add inline start padding to a hidden event line on IRC layout
             cy.setSettingValue("layout", null, SettingLevel.DEVICE, Layout.IRC);
@@ -223,14 +223,20 @@ describe("Timeline", () => {
                 "padding-inline-start",
                 "0px",
             );
-            cy.percySnapshot("Hidden event line with zero padding on IRC layout", { percyCSS });
+
+            cy.get(".mx_MainSplit").percySnapshotElement("Hidden event line with zero padding on IRC layout", {
+                percyCSS,
+            });
 
             // should add inline start padding to a hidden event line on modern layout
             cy.setSettingValue("layout", null, SettingLevel.DEVICE, Layout.Group);
             cy.get(".mx_EventTile[data-layout=group].mx_EventTile_info .mx_EventTile_line")
                 // calc(var(--EventTile_group_line-spacing-inline-start) + 20px) = 64 + 20 = 84px
                 .should("have.css", "padding-inline-start", "84px");
-            cy.percySnapshot("Hidden event line with padding on modern layout", { percyCSS });
+
+            cy.get(".mx_MainSplit").percySnapshotElement("Hidden event line with padding on modern layout", {
+                percyCSS,
+            });
         });
 
         it("should click top left of view source event toggle", () => {
@@ -329,7 +335,12 @@ describe("Timeline", () => {
             cy.wait("@mxc");
 
             cy.checkA11y();
+
+            // Exclude timestamp from snapshot
+            const percyCSS =
+                ".mx_RoomView_body .mx_EventTile_info .mx_MessageTimestamp { visibility: hidden !important; }";
             cy.get(".mx_EventTile_last").percySnapshotElement("URL Preview", {
+                percyCSS,
                 widths: [800, 400],
             });
         });

cypress/e2e/widgets/stickers.spec.ts

@@ -133,6 +133,7 @@ describe("Stickers", () => {
                     type: "m.stickerpicker",
                     name: STICKER_PICKER_WIDGET_NAME,
                     url: stickerPickerUrl,
+                    creatorUserId: "@userId",
                 },
                 id: STICKER_PICKER_WIDGET_ID,
             },

cypress/support/percy.ts

@@ -22,6 +22,7 @@ declare global {
     namespace Cypress {
         interface SnapshotOptions extends PercySnapshotOptions {
             domTransformation?: (documentClone: Document) => void;
+            allowSpinners?: boolean;
         }
 
         interface Chainable {
@@ -38,6 +39,10 @@ declare global {
 }
 
 Cypress.Commands.add("percySnapshotElement", { prevSubject: "element" }, (subject, name, options) => {
+    if (!options?.allowSpinners) {
+        // Await spinners to vanish
+        cy.get(".mx_Spinner").should("not.exist");
+    }
     cy.percySnapshot(name, {
         domTransformation: (documentClone) => scope(documentClone, subject.selector),
         ...options,

package.json

@@ -58,7 +58,7 @@
         "@babel/runtime": "^7.12.5",
         "@matrix-org/analytics-events": "^0.4.0",
         "@matrix-org/matrix-wysiwyg": "^1.1.1",
-        "@matrix-org/react-sdk-module-api": "^0.0.3",
+        "@matrix-org/react-sdk-module-api": "^0.0.4",
         "@sentry/browser": "^7.0.0",
         "@sentry/tracing": "^7.0.0",
         "@testing-library/react-hooks": "^8.0.1",
@@ -92,7 +92,7 @@
         "lodash": "^4.17.20",
         "maplibre-gl": "^2.0.0",
         "matrix-encrypt-attachment": "^1.0.3",
-        "matrix-events-sdk": "0.0.1",
+        "matrix-events-sdk": "2.0.0",
         "matrix-js-sdk": "github:matrix-org/matrix-js-sdk#develop",
         "matrix-widget-api": "^1.1.1",
         "minimist": "^1.2.5",
@@ -111,7 +111,7 @@
         "react-transition-group": "^4.4.1",
         "rfc4648": "^1.4.0",
         "sanitize-filename": "^1.6.3",
-        "sanitize-html": "^2.3.2",
+        "sanitize-html": "2.8.0",
         "tar-js": "^0.3.0",
         "ua-parser-js": "^1.0.2",
         "url": "^0.11.0",
@@ -167,9 +167,8 @@
         "@types/react": "17.0.49",
         "@types/react-beautiful-dnd": "^13.0.0",
         "@types/react-dom": "17.0.17",
-        "@types/react-test-renderer": "^17.0.1",
         "@types/react-transition-group": "^4.4.0",
-        "@types/sanitize-html": "^2.3.1",
+        "@types/sanitize-html": "2.8.0",
         "@types/tar-js": "^0.3.2",
         "@types/ua-parser-js": "^0.7.36",
         "@types/zxcvbn": "^4.4.0",
@@ -212,7 +211,6 @@
         "postcss-scss": "^4.0.4",
         "prettier": "2.8.0",
         "raw-loader": "^4.0.2",
-        "react-test-renderer": "^17.0.2",
         "rimraf": "^3.0.2",
         "stylelint": "^14.9.1",
         "stylelint-config-prettier": "^9.0.4",

res/css/_components.pcss

@@ -18,6 +18,7 @@
 @import "./components/views/beacon/_StyledLiveBeaconIcon.pcss";
 @import "./components/views/context_menus/_KebabContextMenu.pcss";
 @import "./components/views/dialogs/polls/_PollListItem.pcss";
+@import "./components/views/dialogs/polls/_PollListItemEnded.pcss";
 @import "./components/views/elements/_FilterDropdown.pcss";
 @import "./components/views/elements/_FilterTabGroup.pcss";
 @import "./components/views/elements/_LearnMore.pcss";

res/css/components/views/dialogs/polls/_PollListItemEnded.pcss

@@ -0,0 +1,60 @@
+/*
+Copyright 2023 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+.mx_PollListItemEnded {
+    width: 100%;
+    display: flex;
+    flex-direction: column;
+    color: $primary-content;
+}
+
+.mx_PollListItemEnded_title {
+    display: grid;
+    justify-content: left;
+    align-items: center;
+    grid-gap: $spacing-8;
+    grid-template-columns: min-content 1fr min-content;
+    grid-template-rows: auto;
+}
+
+.mx_PollListItemEnded_icon {
+    height: 14px;
+    width: 14px;
+    color: $quaternary-content;
+    padding-left: $spacing-8;
+}
+
+.mx_PollListItemEnded_date {
+    font-size: $font-12px;
+    color: $secondary-content;
+}
+
+.mx_PollListItemEnded_question {
+    white-space: nowrap;
+    overflow: hidden;
+    text-overflow: ellipsis;
+}
+
+.mx_PollListItemEnded_answers {
+    display: grid;
+    grid-gap: $spacing-8;
+    margin-top: $spacing-12;
+}
+
+.mx_PollListItemEnded_voteCount {
+    // 6px to match PollOption padding
+    margin: $spacing-8 0 0 6px;
+}

res/css/components/views/polls/_PollOption.pcss

@@ -18,7 +18,6 @@ limitations under the License.
     border: 1px solid $quinary-content;
     border-radius: 8px;
     padding: 6px 12px;
-    max-width: 550px;
     background-color: $background;
 
     .mx_StyledRadioButton_content,

res/css/views/dialogs/polls/_PollHistoryList.pcss

@@ -32,6 +32,10 @@ limitations under the License.
     grid-gap: $spacing-20;
     padding-right: $spacing-64;
     margin: $spacing-32 0;
+
+    &.mx_PollHistoryList_list_ENDED {
+        grid-gap: $spacing-32;
+    }
 }
 
 .mx_PollHistoryList_noResults {
@@ -42,3 +46,14 @@ limitations under the License.
     justify-content: center;
     color: $secondary-content;
 }
+
+.mx_PollHistoryList_loading {
+    color: $secondary-content;
+    text-align: center;
+
+    // center in all free space
+    // when there are no results
+    &.mx_PollHistoryList_noResultsYet {
+        margin: auto auto;
+    }
+}

res/css/views/elements/_CopyableText.pcss

@@ -23,11 +23,12 @@ limitations under the License.
     max-width: 100%;
 
     &.mx_CopyableText_border {
+        overflow: auto;
         border-radius: 5px;
         border: solid 1px $light-fg-color;
         margin-bottom: 10px;
         margin-top: 10px;
-        padding: 10px;
+        padding: 10px 0 10px 10px;
     }
 
     .mx_CopyableText_copyButton {
@@ -36,11 +37,15 @@ limitations under the License.
         width: 1em;
         height: 1em;
         cursor: pointer;
-        margin-left: 20px;
+        padding-left: 12px;
+        padding-right: 10px;
         display: block;
+        /* If the copy button is used within a scrollable div, make it stick to the right while scrolling */
+        position: sticky;
+        right: 0;
         /* center to first line */
-        position: relative;
         top: 0.15em;
+        background-color: $background;
 
         &::before {
             content: "";

res/css/views/messages/_LegacyCallEvent.pcss

@@ -160,6 +160,7 @@ limitations under the License.
             flex-wrap: wrap;
             align-items: center;
             color: $secondary-content;
+            font-size: $font-12px;
             gap: $spacing-12; /* See mx_IncomingLegacyCallToast_buttons */
             margin-inline-start: 42px; /* avatar (32px) + mx_LegacyCallEvent_info_basic margin (10px) */
             word-break: break-word;
@@ -168,6 +169,7 @@ limitations under the License.
             .mx_LegacyCallEvent_content_button {
                 @mixin LegacyCallButton;
                 padding: 0 $spacing-12;
+                font-size: inherit;
 
                 span::before {
                     mask-size: 16px;

res/css/views/messages/_MPollBody.pcss

@@ -70,4 +70,5 @@ limitations under the License.
     display: grid;
     grid-gap: $spacing-16;
     margin-bottom: $spacing-8;
+    max-width: 550px;
 }

src/AddThreepid.ts

@@ -49,7 +49,7 @@ export type Binding = {
  */
 export default class AddThreepid {
     private sessionId: string;
-    private submitUrl: string;
+    private submitUrl?: string;
     private clientSecret: string;
     private bind: boolean;
 
@@ -93,7 +93,7 @@ export default class AddThreepid {
         if (await MatrixClientPeg.get().doesServerSupportSeparateAddAndBind()) {
             // For separate bind, request a token directly from the IS.
             const authClient = new IdentityAuthClient();
-            const identityAccessToken = await authClient.getAccessToken();
+            const identityAccessToken = (await authClient.getAccessToken()) ?? undefined;
             return MatrixClientPeg.get()
                 .requestEmailToken(emailAddress, this.clientSecret, 1, undefined, identityAccessToken)
                 .then(
@@ -155,7 +155,7 @@ export default class AddThreepid {
         if (await MatrixClientPeg.get().doesServerSupportSeparateAddAndBind()) {
             // For separate bind, request a token directly from the IS.
             const authClient = new IdentityAuthClient();
-            const identityAccessToken = await authClient.getAccessToken();
+            const identityAccessToken = (await authClient.getAccessToken()) ?? undefined;
             return MatrixClientPeg.get()
                 .requestMsisdnToken(phoneCountry, phoneNumber, this.clientSecret, 1, undefined, identityAccessToken)
                 .then(
@@ -184,7 +184,7 @@ export default class AddThreepid {
      * with a "message" property which contains a human-readable message detailing why
      * the request failed.
      */
-    public async checkEmailLinkClicked(): Promise<[boolean, IAuthData | Error | null]> {
+    public async checkEmailLinkClicked(): Promise<[boolean, IAuthData | Error | null] | undefined> {
         try {
             if (await MatrixClientPeg.get().doesServerSupportSeparateAddAndBind()) {
                 if (this.bind) {
@@ -282,7 +282,7 @@ export default class AddThreepid {
      * with a "message" property which contains a human-readable message detailing why
      * the request failed.
      */
-    public async haveMsisdnToken(msisdnToken: string): Promise<any[]> {
+    public async haveMsisdnToken(msisdnToken: string): Promise<any[] | undefined> {
         const authClient = new IdentityAuthClient();
         const supportsSeparateAddAndBind = await MatrixClientPeg.get().doesServerSupportSeparateAddAndBind();
 

src/ContentMessages.ts

@@ -546,7 +546,7 @@ export default class ContentMessages {
             if (upload.cancelled) throw new UploadCanceledError();
             const threadId = relation?.rel_type === THREAD_RELATION_TYPE.name ? relation.event_id : null;
 
-            const response = await matrixClient.sendMessage(roomId, threadId, content);
+            const response = await matrixClient.sendMessage(roomId, threadId ?? null, content);
 
             if (SettingsStore.getValue("Performance.addSendMessageTimingMetadata")) {
                 sendRoundTripMetric(matrixClient, roomId, response.event_id);

src/LegacyCallHandler.tsx

@@ -1024,13 +1024,12 @@ export default class LegacyCallHandler extends EventEmitter {
     }
 
     public answerCall(roomId: string): void {
-        const call = this.calls.get(roomId);
-
-        this.stopRingingIfPossible(call.callId);
-
         // no call to answer
         if (!this.calls.has(roomId)) return;
 
+        const call = this.calls.get(roomId)!;
+        this.stopRingingIfPossible(call.callId);
+
         if (this.getAllActiveCalls().length > 1) {
             Modal.createDialog(ErrorDialog, {
                 title: _t("Too Many Calls"),

src/Lifecycle.ts

@@ -287,7 +287,7 @@ export function handleInvalidStoreError(e: InvalidStoreError): Promise<void> {
                 return MatrixClientPeg.get().store.deleteAllData();
             })
             .then(() => {
-                PlatformPeg.get().reload();
+                PlatformPeg.get()?.reload();
             });
     }
 }
@@ -519,7 +519,7 @@ export async function setLoggedIn(credentials: IMatrixClientCreds): Promise<Matr
     stopMatrixClient();
     const pickleKey =
         credentials.userId && credentials.deviceId
-            ? await PlatformPeg.get().createPickleKey(credentials.userId, credentials.deviceId)
+            ? await PlatformPeg.get()?.createPickleKey(credentials.userId, credentials.deviceId)
             : null;
 
     if (pickleKey) {

src/MatrixClientPeg.ts

@@ -166,7 +166,7 @@ class MatrixClientPegClass implements IMatrixClientPeg {
         }
 
         try {
-            const registrationTime = parseInt(window.localStorage.getItem("mx_registration_time"), 10);
+            const registrationTime = parseInt(window.localStorage.getItem("mx_registration_time")!, 10);
             const diff = Date.now() - registrationTime;
             return diff / 36e5 <= hours;
         } catch (e) {
@@ -176,7 +176,7 @@ class MatrixClientPegClass implements IMatrixClientPeg {
 
     public userRegisteredAfter(timestamp: Date): boolean {
         try {
-            const registrationTime = parseInt(window.localStorage.getItem("mx_registration_time"), 10);
+            const registrationTime = parseInt(window.localStorage.getItem("mx_registration_time")!, 10);
             return timestamp.getTime() <= registrationTime;
         } catch (e) {
             return false;
@@ -292,7 +292,7 @@ class MatrixClientPegClass implements IMatrixClientPeg {
     }
 
     public getCredentials(): IMatrixClientCreds {
-        let copiedCredentials = this.currentClientCreds;
+        let copiedCredentials: IMatrixClientCreds | null = this.currentClientCreds;
         if (this.currentClientCreds?.userId !== this.matrixClient?.credentials?.userId) {
             // cached credentials belong to a different user - don't use them
             copiedCredentials = null;

src/MediaDeviceHandler.ts

@@ -64,7 +64,7 @@ export default class MediaDeviceHandler extends EventEmitter {
      *
      * @return Promise<IMediaDevices> The available media devices
      */
-    public static async getDevices(): Promise<IMediaDevices> {
+    public static async getDevices(): Promise<IMediaDevices | undefined> {
         try {
             const devices = await navigator.mediaDevices.enumerateDevices();
             const output: Record<MediaDeviceKindEnum, MediaDeviceInfo[]> = {

src/PosthogTrackers.ts

@@ -54,8 +54,8 @@ export default class PosthogTrackers {
     }
 
     private view: Views = Views.LOADING;
-    private pageType?: PageType = null;
+    private pageType?: PageType;
-    private override?: ScreenName = null;
+    private override?: ScreenName;
 
     public trackPageChange(view: Views, pageType: PageType | undefined, durationMs: number): void {
         this.view = view;
@@ -66,7 +66,7 @@ export default class PosthogTrackers {
 
     private trackPage(durationMs?: number): void {
         const screenName =
-            this.view === Views.LOGGED_IN ? loggedInPageTypeMap[this.pageType] : notLoggedInMap[this.view];
+            this.view === Views.LOGGED_IN ? loggedInPageTypeMap[this.pageType!] : notLoggedInMap[this.view];
         PosthogAnalytics.instance.trackEvent<ScreenEvent>({
             eventName: "$pageview",
             $current_url: screenName,
@@ -85,7 +85,7 @@ export default class PosthogTrackers {
 
     public clearOverride(screenName: ScreenName): void {
         if (screenName !== this.override) return;
-        this.override = null;
+        this.override = undefined;
         this.trackPage();
     }
 

src/SdkConfig.ts

@@ -26,7 +26,6 @@ export const DEFAULTS: IConfigOptions = {
     brand: "Element",
     integrations_ui_url: "https://scalar.vector.im/",
     integrations_rest_url: "https://scalar.vector.im/api",
-    bug_report_endpoint_url: null,
     uisi_autorageshake_app: "element-auto-uisi",
 
     jitsi: {

src/SlashCommands.tsx

@@ -198,7 +198,7 @@ function reject(error?: any): RunResult {
     return { error };
 }
 
-function success(promise?: Promise<any>): RunResult {
+function success(promise: Promise<any> = Promise.resolve()): RunResult {
     return { promise };
 }
 
@@ -221,7 +221,7 @@ export const Commands = [
         command: "spoiler",
         args: "<message>",
         description: _td("Sends the given message as a spoiler"),
-        runFn: function (roomId, message) {
+        runFn: function (roomId, message = "") {
             return successSync(ContentHelpers.makeHtmlMessage(message, `<span data-mx-spoiler>${message}</span>`));
         },
         category: CommandCategories.messages,
@@ -282,7 +282,7 @@ export const Commands = [
         command: "plain",
         args: "<message>",
         description: _td("Sends a message as plain text, without interpreting it as markdown"),
-        runFn: function (roomId, messages) {
+        runFn: function (roomId, messages = "") {
             return successSync(ContentHelpers.makeTextMessage(messages));
         },
         category: CommandCategories.messages,
@@ -291,7 +291,7 @@ export const Commands = [
         command: "html",
         args: "<message>",
         description: _td("Sends a message as html, without interpreting it as markdown"),
-        runFn: function (roomId, messages) {
+        runFn: function (roomId, messages = "") {
             return successSync(ContentHelpers.makeHtmlMessage(messages, messages));
         },
         category: CommandCategories.messages,

src/autocomplete/Autocompleter.ts

@@ -27,6 +27,7 @@ import { timeout } from "../utils/promise";
 import AutocompleteProvider, { ICommand } from "./AutocompleteProvider";
 import SpaceProvider from "./SpaceProvider";
 import { TimelineRenderingType } from "../contexts/RoomContext";
+import { filterBoolean } from "../utils/arrays";
 
 export interface ISelectionRange {
     beginning?: boolean; // whether the selection is in the first block of the editor or not
@@ -55,7 +56,7 @@ const PROVIDER_COMPLETION_TIMEOUT = 3000;
 export interface IProviderCompletions {
     completions: ICompletion[];
     provider: AutocompleteProvider;
-    command: ICommand;
+    command: Partial<ICommand>;
 }
 
 export default class Autocompleter {
@@ -98,8 +99,8 @@ export default class Autocompleter {
         );
 
         // map then filter to maintain the index for the map-operation, for this.providers to line up
-        return completionsList
+        return filterBoolean(
-            .map((completions, i) => {
+            completionsList.map((completions, i) => {
                 if (!completions || !completions.length) return;
 
                 return {
@@ -112,7 +113,7 @@ export default class Autocompleter {
                      */
                     command: this.providers[i].getCurrentCommand(query, selection, force),
                 };
-            })
+            }),
-            .filter(Boolean) as IProviderCompletions[];
+        );
     }
 }

src/autocomplete/EmojiProvider.tsx

@@ -32,6 +32,7 @@ import SettingsStore from "../settings/SettingsStore";
 import { EMOJI, IEmoji, getEmojiFromUnicode } from "../emoji";
 import { TimelineRenderingType } from "../contexts/RoomContext";
 import * as recent from "../emojipicker/recent";
+import { filterBoolean } from "../utils/arrays";
 
 const LIMIT = 20;
 
@@ -94,7 +95,7 @@ export default class EmojiProvider extends AutocompleteProvider {
             shouldMatchWordsOnly: true,
         });
 
-        this.recentlyUsed = Array.from(new Set(recent.get().map(getEmojiFromUnicode).filter(Boolean))) as IEmoji[];
+        this.recentlyUsed = Array.from(new Set(filterBoolean(recent.get().map(getEmojiFromUnicode))));
     }
 
     public async getCompletions(

src/components/structures/EmbeddedPage.tsx

@@ -46,7 +46,7 @@ interface IState {
 export default class EmbeddedPage extends React.PureComponent<IProps, IState> {
     public static contextType = MatrixClientContext;
     private unmounted = false;
-    private dispatcherRef: string = null;
+    private dispatcherRef: string | null = null;
 
     public constructor(props: IProps, context: typeof MatrixClientContext) {
         super(props, context);
@@ -64,7 +64,7 @@ export default class EmbeddedPage extends React.PureComponent<IProps, IState> {
         let res: Response;
 
         try {
-            res = await fetch(this.props.url, { method: "GET" });
+            res = await fetch(this.props.url!, { method: "GET" });
         } catch (err) {
             if (this.unmounted) return;
             logger.warn(`Error loading page: ${err}`);
@@ -84,7 +84,7 @@ export default class EmbeddedPage extends React.PureComponent<IProps, IState> {
 
         if (this.props.replaceMap) {
             Object.keys(this.props.replaceMap).forEach((key) => {
-                body = body.split(key).join(this.props.replaceMap[key]);
+                body = body.split(key).join(this.props.replaceMap![key]);
             });
         }
 
@@ -123,8 +123,7 @@ export default class EmbeddedPage extends React.PureComponent<IProps, IState> {
         const client = this.context || MatrixClientPeg.get();
         const isGuest = client ? client.isGuest() : true;
         const className = this.props.className;
-        const classes = classnames({
+        const classes = classnames(className, {
-            [className]: true,
             [`${className}_guest`]: isGuest,
             [`${className}_loggedIn`]: !!client,
         });

src/components/structures/FileDropTarget.tsx

@@ -40,6 +40,7 @@ const FileDropTarget: React.FC<IProps> = ({ parent, onFileDrop }) => {
         const onDragEnter = (ev: DragEvent): void => {
             ev.stopPropagation();
             ev.preventDefault();
+            if (!ev.dataTransfer) return;
 
             setState((state) => ({
                 // We always increment the counter no matter the types, because dragging is
@@ -49,7 +50,8 @@ const FileDropTarget: React.FC<IProps> = ({ parent, onFileDrop }) => {
                 // https://docs.w3cub.com/dom/datatransfer/types
                 // https://developer.mozilla.org/en-US/docs/Web/API/HTML_Drag_and_Drop_API/Recommended_drag_types#file
                 dragging:
-                    ev.dataTransfer.types.includes("Files") || ev.dataTransfer.types.includes("application/x-moz-file")
+                    ev.dataTransfer!.types.includes("Files") ||
+                    ev.dataTransfer!.types.includes("application/x-moz-file")
                         ? true
                         : state.dragging,
             }));
@@ -68,6 +70,7 @@ const FileDropTarget: React.FC<IProps> = ({ parent, onFileDrop }) => {
         const onDragOver = (ev: DragEvent): void => {
             ev.stopPropagation();
             ev.preventDefault();
+            if (!ev.dataTransfer) return;
 
             ev.dataTransfer.dropEffect = "none";
 
@@ -82,6 +85,7 @@ const FileDropTarget: React.FC<IProps> = ({ parent, onFileDrop }) => {
         const onDrop = (ev: DragEvent): void => {
             ev.stopPropagation();
             ev.preventDefault();
+            if (!ev.dataTransfer) return;
             onFileDrop(ev.dataTransfer);
 
             setState((state) => ({

src/components/structures/FilePanel.tsx

@@ -66,7 +66,7 @@ class FilePanel extends React.Component<IProps, IState> {
 
     private onRoomTimeline = (
         ev: MatrixEvent,
-        room: Room | null,
+        room: Room | undefined,
         toStartOfTimeline: boolean,
         removed: boolean,
         data: IRoomTimelineData,
@@ -78,7 +78,7 @@ class FilePanel extends React.Component<IProps, IState> {
         client.decryptEventIfNeeded(ev);
 
         if (ev.isBeingDecrypted()) {
-            this.decryptingEvents.add(ev.getId());
+            this.decryptingEvents.add(ev.getId()!);
         } else {
             this.addEncryptedLiveEvent(ev);
         }
@@ -86,7 +86,7 @@ class FilePanel extends React.Component<IProps, IState> {
 
     private onEventDecrypted = (ev: MatrixEvent, err?: any): void => {
         if (ev.getRoomId() !== this.props.roomId) return;
-        const eventId = ev.getId();
+        const eventId = ev.getId()!;
 
         if (!this.decryptingEvents.delete(eventId)) return;
         if (err) return;
@@ -103,7 +103,7 @@ class FilePanel extends React.Component<IProps, IState> {
             return;
         }
 
-        if (!this.state.timelineSet.eventIdToTimeline(ev.getId())) {
+        if (!this.state.timelineSet.eventIdToTimeline(ev.getId()!)) {
             this.state.timelineSet.addEventToTimeline(ev, timeline, false);
         }
     }

src/components/structures/HomePage.tsx

@@ -56,15 +56,15 @@ const getOwnProfile = (
     userId: string,
 ): {
     displayName: string;
-    avatarUrl: string;
+    avatarUrl?: string;
 } => ({
     displayName: OwnProfileStore.instance.displayName || userId,
-    avatarUrl: OwnProfileStore.instance.getHttpAvatarUrl(AVATAR_SIZE),
+    avatarUrl: OwnProfileStore.instance.getHttpAvatarUrl(AVATAR_SIZE) ?? undefined,
 });
 
 const UserWelcomeTop: React.FC = () => {
     const cli = useContext(MatrixClientContext);
-    const userId = cli.getUserId();
+    const userId = cli.getUserId()!;
     const [ownProfile, setOwnProfile] = useState(getOwnProfile(userId));
     useEventEmitter(OwnProfileStore.instance, UPDATE_EVENT, () => {
         setOwnProfile(getOwnProfile(userId));

src/components/structures/InteractiveAuth.tsx

@@ -33,7 +33,7 @@ export const ERROR_USER_CANCELLED = new Error("User cancelled auth session");
 
 type InteractiveAuthCallbackSuccess = (
     success: true,
-    response: IAuthData,
+    response?: IAuthData,
     extra?: { emailSid?: string; clientSecret?: string },
 ) => void;
 type InteractiveAuthCallbackFailure = (success: false, response: IAuthData | Error) => void;
@@ -94,7 +94,7 @@ interface IState {
 
 export default class InteractiveAuthComponent extends React.Component<IProps, IState> {
     private readonly authLogic: InteractiveAuth;
-    private readonly intervalId: number = null;
+    private readonly intervalId: number | null = null;
     private readonly stageComponent = createRef<IStageComponent>();
 
     private unmounted = false;
@@ -103,10 +103,7 @@ export default class InteractiveAuthComponent extends React.Component<IProps, IS
         super(props);
 
         this.state = {
-            authStage: null,
             busy: false,
-            errorText: null,
-            errorCode: null,
             submitButtonEnabled: false,
         };
 
@@ -213,8 +210,8 @@ export default class InteractiveAuthComponent extends React.Component<IProps, IS
         if (busy) {
             this.setState({
                 busy: true,
-                errorText: null,
+                errorText: undefined,
-                errorCode: null,
+                errorCode: undefined,
             });
         }
         // The JS SDK eagerly reports itself as "not busy" right after any

src/components/structures/LeftPanel.tsx

@@ -166,10 +166,11 @@ export default class LeftPanel extends React.Component<IProps, IState> {
             }
         >();
 
-        let lastTopHeader;
+        let lastTopHeader: HTMLDivElement | undefined;
-        let firstBottomHeader;
+        let firstBottomHeader: HTMLDivElement | undefined;
         for (const sublist of sublists) {
             const header = sublist.querySelector<HTMLDivElement>(".mx_RoomSublist_stickable");
+            if (!header) continue; // this should never occur
             header.style.removeProperty("display"); // always clear display:none first
 
             // When an element is <=40% off screen, make it take over
@@ -196,7 +197,7 @@ export default class LeftPanel extends React.Component<IProps, IState> {
         // cause a no-op update, as adding/removing properties that are/aren't there cause
         // layout updates.
         for (const header of targetStyles.keys()) {
-            const style = targetStyles.get(header);
+            const style = targetStyles.get(header)!;
 
             if (style.makeInvisible) {
                 // we will have already removed the 'display: none', so add it back.
@@ -324,7 +325,7 @@ export default class LeftPanel extends React.Component<IProps, IState> {
     }
 
     private renderSearchDialExplore(): React.ReactNode {
-        let dialPadButton = null;
+        let dialPadButton: JSX.Element | undefined;
 
         // If we have dialer support, show a button to bring up the dial pad
         // to start a new call
@@ -338,7 +339,7 @@ export default class LeftPanel extends React.Component<IProps, IState> {
             );
         }
 
-        let rightButton: JSX.Element;
+        let rightButton: JSX.Element | undefined;
         if (this.state.showBreadcrumbs === BreadcrumbsMode.Labs) {
             rightButton = <RecentlyViewedButton />;
         } else if (this.state.activeSpace === MetaSpace.Home && shouldShowComponent(UIComponent.ExploreRooms)) {

src/components/structures/LegacyCallEventGrouper.ts

@@ -35,7 +35,7 @@ const CONNECTING_STATES = [
     CallState.CreateAnswer,
 ];
 
-const SUPPORTED_STATES = [CallState.Connected, CallState.Ringing];
+const SUPPORTED_STATES = [CallState.Connected, CallState.Ringing, CallState.Ended];
 
 export enum CustomCallState {
     Missed = "missed",
@@ -72,7 +72,7 @@ export function buildLegacyCallEventGroupers(
 
 export default class LegacyCallEventGrouper extends EventEmitter {
     private events: Set<MatrixEvent> = new Set<MatrixEvent>();
-    private call: MatrixCall;
+    private call: MatrixCall | null = null;
     public state: CallState | CustomCallState;
 
     public constructor() {
@@ -111,7 +111,7 @@ export default class LegacyCallEventGrouper extends EventEmitter {
     }
 
     public get hangupReason(): string | null {
-        return this.hangup?.getContent()?.reason;
+        return this.call?.hangupReason ?? this.hangup?.getContent()?.reason ?? null;
     }
 
     public get rejectParty(): string {

src/components/structures/MatrixChat.tsx

@@ -226,8 +226,6 @@ export default class MatrixChat extends React.PureComponent<IProps, IState> {
 
     private screenAfterLogin?: IScreen;
     private tokenLogin?: boolean;
-    private accountPassword?: string;
-    private accountPasswordTimer?: number;
     private focusComposer: boolean;
     private subTitleStatus: string;
     private prevWindowWidth: number;
@@ -296,9 +294,6 @@ export default class MatrixChat extends React.PureComponent<IProps, IState> {
             Lifecycle.loadSession();
         }
 
-        this.accountPassword = null;
-        this.accountPasswordTimer = null;
-
         this.dispatcherRef = dis.register(this.onAction);
 
         this.themeWatcher = new ThemeWatcher();
@@ -439,7 +434,7 @@ export default class MatrixChat extends React.PureComponent<IProps, IState> {
         this.state.resizeNotifier.removeListener("middlePanelResized", this.dispatchTimelineResize);
         window.removeEventListener("resize", this.onWindowResized);
 
-        if (this.accountPasswordTimer !== null) clearTimeout(this.accountPasswordTimer);
+        this.stores.accountPasswordStore.clearPassword();
         if (this.voiceBroadcastResumer) this.voiceBroadcastResumer.destroy();
     }
 
@@ -1987,13 +1982,7 @@ export default class MatrixChat extends React.PureComponent<IProps, IState> {
      * this, as they instead jump straight into the app after `attemptTokenLogin`.
      */
     private onUserCompletedLoginFlow = async (credentials: IMatrixClientCreds, password: string): Promise<void> => {
-        this.accountPassword = password;
+        this.stores.accountPasswordStore.setPassword(password);
-        // self-destruct the password after 5mins
-        if (this.accountPasswordTimer !== null) clearTimeout(this.accountPasswordTimer);
-        this.accountPasswordTimer = window.setTimeout(() => {
-            this.accountPassword = null;
-            this.accountPasswordTimer = null;
-        }, 60 * 5 * 1000);
 
         // Create and start the client
         await Lifecycle.setLoggedIn(credentials);
@@ -2037,7 +2026,7 @@ export default class MatrixChat extends React.PureComponent<IProps, IState> {
             view = (
                 <E2eSetup
                     onFinished={this.onCompleteSecurityE2eSetupFinished}
-                    accountPassword={this.accountPassword}
+                    accountPassword={this.stores.accountPasswordStore.getPassword()}
                     tokenLogin={!!this.tokenLogin}
                 />
             );

src/components/structures/RoomView.tsx

@@ -114,8 +114,11 @@ import { RoomSearchView } from "./RoomSearchView";
 import eventSearch from "../../Searching";
 import VoipUserMapper from "../../VoipUserMapper";
 import { isCallEvent } from "./LegacyCallEventGrouper";
+import { WidgetType } from "../../widgets/WidgetType";
+import WidgetUtils from "../../utils/WidgetUtils";
 
 const DEBUG = false;
+const PREVENT_MULTIPLE_JITSI_WITHIN = 30_000;
 let debuglog = function (msg: string): void {};
 
 const BROWSER_SUPPORTS_SANDBOX = "sandbox" in document.createElement("iframe");
@@ -483,6 +486,7 @@ export class RoomView extends React.Component<IRoomProps, IRoomState> {
     private onWidgetStoreUpdate = (): void => {
         if (!this.state.room) return;
         this.checkWidgets(this.state.room);
+        this.doMaybeRemoveOwnJitsiWidget();
     };
 
     private onWidgetEchoStoreUpdate = (): void => {
@@ -503,6 +507,56 @@ export class RoomView extends React.Component<IRoomProps, IRoomState> {
         this.checkWidgets(this.state.room);
     };
 
+    /**
+     * Removes the Jitsi widget from the current user if
+     * - Multiple Jitsi widgets have been added within {@link PREVENT_MULTIPLE_JITSI_WITHIN}
+     * - The last (server timestamp) of these widgets is from the currrent user
+     * This solves the issue if some people decide to start a conference and click the call button at the same time.
+     */
+    private doMaybeRemoveOwnJitsiWidget(): void {
+        if (!this.state.roomId || !this.state.room || !this.context.client) return;
+
+        const apps = this.context.widgetStore.getApps(this.state.roomId);
+        const jitsiApps = apps.filter((app) => app.eventId && WidgetType.JITSI.matches(app.type));
+
+        // less than two Jitsi widgets → nothing to do
+        if (jitsiApps.length < 2) return;
+
+        const currentUserId = this.context.client.getSafeUserId();
+        const createdByCurrentUser = jitsiApps.find((apps) => apps.creatorUserId === currentUserId);
+
+        // no Jitsi widget from current user → nothing to do
+        if (!createdByCurrentUser) return;
+
+        const createdByCurrentUserEvent = this.state.room.findEventById(createdByCurrentUser.eventId!);
+
+        // widget event not found → nothing can be done
+        if (!createdByCurrentUserEvent) return;
+
+        const createdByCurrentUserTs = createdByCurrentUserEvent.getTs();
+
+        // widget timestamp is empty → nothing can be done
+        if (!createdByCurrentUserTs) return;
+
+        const lastCreatedByOtherTs = jitsiApps.reduce((maxByNow: number, app) => {
+            if (app.eventId === createdByCurrentUser.eventId) return maxByNow;
+
+            const appCreateTs = this.state.room!.findEventById(app.eventId!)?.getTs() || 0;
+            return Math.max(maxByNow, appCreateTs);
+        }, 0);
+
+        // last widget timestamp from other is empty → nothing can be done
+        if (!lastCreatedByOtherTs) return;
+
+        if (
+            createdByCurrentUserTs > lastCreatedByOtherTs &&
+            createdByCurrentUserTs - lastCreatedByOtherTs < PREVENT_MULTIPLE_JITSI_WITHIN
+        ) {
+            // more than one Jitsi widget with the last one from the current user → remove it
+            WidgetUtils.setRoomWidget(this.state.roomId, createdByCurrentUser.id);
+        }
+    }
+
     private checkWidgets = (room: Room): void => {
         this.setState({
             hasPinnedWidgets: this.context.widgetLayoutStore.hasPinnedWidgets(room),
@@ -1903,6 +1957,7 @@ export class RoomView extends React.Component<IRoomProps, IRoomState> {
                                 loading={loading}
                                 joining={this.state.joining}
                                 oobData={this.props.oobData}
+                                roomId={this.state.roomId}
                             />
                         </ErrorBoundary>
                     </div>
@@ -1932,7 +1987,7 @@ export class RoomView extends React.Component<IRoomProps, IRoomState> {
                                 invitedEmail={invitedEmail}
                                 oobData={this.props.oobData}
                                 signUrl={this.props.threepidInvite?.signUrl}
-                                room={this.state.room}
+                                roomId={this.state.roomId}
                             />
                         </ErrorBoundary>
                     </div>
@@ -1969,6 +2024,7 @@ export class RoomView extends React.Component<IRoomProps, IRoomState> {
                             error={this.state.roomLoadError}
                             joining={this.state.joining}
                             rejecting={this.state.rejecting}
+                            roomId={this.state.roomId}
                         />
                     </ErrorBoundary>
                 );
@@ -1998,6 +2054,7 @@ export class RoomView extends React.Component<IRoomProps, IRoomState> {
                                 canPreview={false}
                                 joining={this.state.joining}
                                 room={this.state.room}
+                                roomId={this.state.roomId}
                             />
                         </ErrorBoundary>
                     </div>
@@ -2090,6 +2147,7 @@ export class RoomView extends React.Component<IRoomProps, IRoomState> {
                     oobData={this.props.oobData}
                     canPreview={this.state.canPeek}
                     room={this.state.room}
+                    roomId={this.state.roomId}
                 />
             );
             if (!this.state.canPeek && !this.state.room?.isSpaceRoom()) {

src/components/structures/ViewSource.tsx

@@ -139,15 +139,15 @@ export default class ViewSource extends React.Component<IProps, IState> {
     private canSendStateEvent(mxEvent: MatrixEvent): boolean {
         const cli = MatrixClientPeg.get();
         const room = cli.getRoom(mxEvent.getRoomId());
-        return room.currentState.mayClientSendStateEvent(mxEvent.getType(), cli);
+        return !!room?.currentState.mayClientSendStateEvent(mxEvent.getType(), cli);
     }
 
     public render(): React.ReactNode {
         const mxEvent = this.props.mxEvent.replacingEvent() || this.props.mxEvent; // show the replacing event, not the original, if it is an edit
 
         const isEditing = this.state.isEditing;
-        const roomId = mxEvent.getRoomId();
+        const roomId = mxEvent.getRoomId()!;
-        const eventId = mxEvent.getId();
+        const eventId = mxEvent.getId()!;
         const canEdit = mxEvent.isState() ? this.canSendStateEvent(mxEvent) : canEditContent(this.props.mxEvent);
         return (
             <BaseDialog className="mx_ViewSource" onFinished={this.props.onFinished} title={_t("View Source")}>

src/components/structures/auth/Login.tsx

@@ -39,6 +39,7 @@ import AuthBody from "../../views/auth/AuthBody";
 import AuthHeader from "../../views/auth/AuthHeader";
 import AccessibleButton, { ButtonEvent } from "../../views/elements/AccessibleButton";
 import { ValidatedServerConfig } from "../../../utils/ValidatedServerConfig";
+import { filterBoolean } from "../../../utils/arrays";
 
 // These are used in several places, and come from the js-sdk's autodiscovery
 // stuff. We define them here so that they'll be picked up by i18n.
@@ -120,15 +121,11 @@ export default class LoginComponent extends React.PureComponent<IProps, IState>
 
         this.state = {
             busy: false,
-            busyLoggingIn: null,
             errorText: null,
             loginIncorrect: false,
             canTryLogin: true,
 
-            flows: null,
-
             username: props.defaultUsername ? props.defaultUsername : "",
-            phoneCountry: null,
             phoneNumber: "",
 
             serverIsAlive: true,
@@ -167,7 +164,7 @@ export default class LoginComponent extends React.PureComponent<IProps, IState>
         }
     }
 
-    public isBusy = (): boolean => this.state.busy || this.props.busy;
+    public isBusy = (): boolean => !!this.state.busy || !!this.props.busy;
 
     public onPasswordLogin: OnPasswordLogin = async (
         username: string | undefined,
@@ -349,7 +346,7 @@ export default class LoginComponent extends React.PureComponent<IProps, IState>
             ev.preventDefault();
             ev.stopPropagation();
             const ssoKind = ssoFlow.type === "m.login.sso" ? "sso" : "cas";
-            PlatformPeg.get().startSingleSignOn(
+            PlatformPeg.get()?.startSingleSignOn(
                 this.loginLogic.createTemporaryClient(),
                 ssoKind,
                 this.props.fragmentAfterLogin,
@@ -511,13 +508,13 @@ export default class LoginComponent extends React.PureComponent<IProps, IState>
         return errorText;
     }
 
-    public renderLoginComponentForFlows(): JSX.Element {
+    public renderLoginComponentForFlows(): ReactNode {
         if (!this.state.flows) return null;
 
         // this is the ideal order we want to show the flows in
         const order = ["m.login.password", "m.login.sso"];
 
-        const flows = order.map((type) => this.state.flows.find((flow) => flow.type === type)).filter(Boolean);
+        const flows = filterBoolean(order.map((type) => this.state.flows.find((flow) => flow.type === type)));
         return (
             <React.Fragment>
                 {flows.map((flow) => {

src/components/views/auth/CaptchaForm.tsx

@@ -65,7 +65,7 @@ export default class CaptchaForm extends React.Component<ICaptchaFormProps, ICap
                 "src",
                 `https://www.recaptcha.net/recaptcha/api.js?onload=mxOnRecaptchaLoaded&render=explicit`,
             );
-            this.recaptchaContainer.current.appendChild(scriptTag);
+            this.recaptchaContainer.current?.appendChild(scriptTag);
         }
     }
 
@@ -95,7 +95,7 @@ export default class CaptchaForm extends React.Component<ICaptchaFormProps, ICap
         }
 
         logger.info("Rendering to %s", divId);
-        this.captchaWidgetId = global.grecaptcha.render(divId, {
+        this.captchaWidgetId = global.grecaptcha?.render(divId, {
             sitekey: publicKey,
             callback: this.props.onCaptchaResponse,
         });
@@ -113,7 +113,7 @@ export default class CaptchaForm extends React.Component<ICaptchaFormProps, ICap
             this.renderRecaptcha(DIV_ID);
             // clear error if re-rendered
             this.setState({
-                errorText: null,
+                errorText: undefined,
             });
         } catch (e) {
             this.setState({
@@ -123,7 +123,7 @@ export default class CaptchaForm extends React.Component<ICaptchaFormProps, ICap
     }
 
     public render(): React.ReactNode {
-        let error = null;
+        let error: JSX.Element | undefined;
         if (this.state.errorText) {
             error = <div className="error">{this.state.errorText}</div>;
         }

src/components/views/auth/EmailField.tsx

@@ -50,12 +50,12 @@ class EmailField extends PureComponent<IProps> {
             {
                 key: "required",
                 test: ({ value, allowEmpty }) => allowEmpty || !!value,
-                invalid: () => _t(this.props.labelRequired),
+                invalid: () => _t(this.props.labelRequired!),
             },
             {
                 key: "email",
                 test: ({ value }) => !value || Email.looksValid(value),
-                invalid: () => _t(this.props.labelInvalid),
+                invalid: () => _t(this.props.labelInvalid!),
             },
         ],
     });
@@ -80,7 +80,7 @@ class EmailField extends PureComponent<IProps> {
                 id={this.props.id}
                 ref={this.props.fieldRef}
                 type="text"
-                label={_t(this.props.label)}
+                label={_t(this.props.label!)}
                 value={this.props.value}
                 autoFocus={this.props.autoFocus}
                 onChange={this.props.onChange}

src/components/views/auth/PasswordLogin.tsx

@@ -36,7 +36,7 @@ interface IProps {
     phoneNumber: string;
 
     serverConfig: ValidatedServerConfig;
-    loginIncorrect?: boolean;
+    loginIncorrect: boolean;
     disableSubmit?: boolean;
     busy?: boolean;
 
@@ -67,9 +67,9 @@ const enum LoginField {
  * The email/username/phone fields are fully-controlled, the password field is not.
  */
 export default class PasswordLogin extends React.PureComponent<IProps, IState> {
-    private [LoginField.Email]: Field;
+    private [LoginField.Email]: Field | null;
-    private [LoginField.Phone]: Field;
+    private [LoginField.Phone]: Field | null;
-    private [LoginField.MatrixId]: Field;
+    private [LoginField.MatrixId]: Field | null;
 
     public static defaultProps = {
         onUsernameChanged: function () {},
@@ -93,7 +93,7 @@ export default class PasswordLogin extends React.PureComponent<IProps, IState> {
     private onForgotPasswordClick = (ev: ButtonEvent): void => {
         ev.preventDefault();
         ev.stopPropagation();
-        this.props.onForgotPasswordClick();
+        this.props.onForgotPasswordClick?.();
     };
 
     private onSubmitForm = async (ev: SyntheticEvent): Promise<void> => {
@@ -116,25 +116,25 @@ export default class PasswordLogin extends React.PureComponent<IProps, IState> {
     };
 
     private onUsernameChanged = (ev: React.ChangeEvent<HTMLInputElement>): void => {
-        this.props.onUsernameChanged(ev.target.value);
+        this.props.onUsernameChanged?.(ev.target.value);
     };
 
     private onUsernameBlur = (ev: React.FocusEvent<HTMLInputElement>): void => {
-        this.props.onUsernameBlur(ev.target.value);
+        this.props.onUsernameBlur?.(ev.target.value);
     };
 
     private onLoginTypeChange = (ev: React.ChangeEvent<HTMLSelectElement>): void => {
         const loginType = ev.target.value as IState["loginType"];
         this.setState({ loginType });
-        this.props.onUsernameChanged(""); // Reset because email and username use the same state
+        this.props.onUsernameChanged?.(""); // Reset because email and username use the same state
     };
 
     private onPhoneCountryChanged = (country: PhoneNumberCountryDefinition): void => {
-        this.props.onPhoneCountryChanged(country.iso2);
+        this.props.onPhoneCountryChanged?.(country.iso2);
     };
 
     private onPhoneNumberChanged = (ev: React.ChangeEvent<HTMLInputElement>): void => {
-        this.props.onPhoneNumberChanged(ev.target.value);
+        this.props.onPhoneNumberChanged?.(ev.target.value);
     };
 
     private onPasswordChanged = (ev: React.ChangeEvent<HTMLInputElement>): void => {
@@ -199,7 +199,7 @@ export default class PasswordLogin extends React.PureComponent<IProps, IState> {
         return null;
     }
 
-    private markFieldValid(fieldID: LoginField, valid: boolean): void {
+    private markFieldValid(fieldID: LoginField, valid?: boolean): void {
         const { fieldValid } = this.state;
         fieldValid[fieldID] = valid;
         this.setState({
@@ -368,7 +368,7 @@ export default class PasswordLogin extends React.PureComponent<IProps, IState> {
     }
 
     public render(): React.ReactNode {
-        let forgotPasswordJsx;
+        let forgotPasswordJsx: JSX.Element | undefined;
 
         if (this.props.onForgotPasswordClick) {
             forgotPasswordJsx = (

src/components/views/auth/Welcome.tsx

@@ -34,7 +34,7 @@ interface IProps {}
 export default class Welcome extends React.PureComponent<IProps> {
     public render(): React.ReactNode {
         const pagesConfig = SdkConfig.getObject("embedded_pages");
-        let pageUrl = null;
+        let pageUrl!: string;
         if (pagesConfig) {
             pageUrl = pagesConfig.get("welcome_url");
         }

src/components/views/beacon/BeaconViewDialog.tsx

@@ -158,12 +158,12 @@ const BeaconViewDialog: React.FC<IProps> = ({ initialFocusedBeacon, roomId, matr
                 )}
                 {mapDisplayError && <MapError error={mapDisplayError.message as LocationShareError} isMinimised />}
                 {!centerGeoUri && !mapDisplayError && (
-                    <MapFallback data-test-id="beacon-view-dialog-map-fallback" className="mx_BeaconViewDialog_map">
+                    <MapFallback data-testid="beacon-view-dialog-map-fallback" className="mx_BeaconViewDialog_map">
                         <span className="mx_BeaconViewDialog_mapFallbackMessage">{_t("No live locations")}</span>
                         <AccessibleButton
                             kind="primary"
                             onClick={onFinished}
-                            data-test-id="beacon-view-dialog-fallback-close"
+                            data-testid="beacon-view-dialog-fallback-close"
                         >
                             {_t("Close")}
                         </AccessibleButton>
@@ -179,7 +179,7 @@ const BeaconViewDialog: React.FC<IProps> = ({ initialFocusedBeacon, roomId, matr
                     <AccessibleButton
                         kind="primary"
                         onClick={() => setSidebarOpen(true)}
-                        data-test-id="beacon-view-dialog-open-sidebar"
+                        data-testid="beacon-view-dialog-open-sidebar"
                         className="mx_BeaconViewDialog_viewListButton"
                     >
                         <LiveLocationIcon height={12} />

src/components/views/context_menus/WidgetContextMenu.tsx

@@ -17,6 +17,7 @@ limitations under the License.
 import React, { useContext } from "react";
 import { MatrixCapabilities } from "matrix-widget-api";
 import { logger } from "matrix-js-sdk/src/logger";
+import { ApprovalOpts, WidgetLifecycle } from "@matrix-org/react-sdk-module-api/lib/lifecycles/WidgetLifecycle";
 
 import IconizedContextMenu, { IconizedContextMenuOption, IconizedContextMenuOptionList } from "./IconizedContextMenu";
 import { ChevronFace } from "../../structures/ContextMenu";
@@ -34,6 +35,8 @@ import { WidgetType } from "../../../widgets/WidgetType";
 import MatrixClientContext from "../../../contexts/MatrixClientContext";
 import { Container, WidgetLayoutStore } from "../../../stores/widgets/WidgetLayoutStore";
 import { getConfigLivestreamUrl, startJitsiAudioLivestream } from "../../../Livestream";
+import { ModuleRunner } from "../../../modules/ModuleRunner";
+import { ElementWidget } from "../../../stores/widgets/StopGapWidget";
 
 interface IProps extends React.ComponentProps<typeof IconizedContextMenu> {
     app: IApp;
@@ -45,7 +48,7 @@ interface IProps extends React.ComponentProps<typeof IconizedContextMenu> {
     onEditClick?(): void;
 }
 
-const WidgetContextMenu: React.FC<IProps> = ({
+export const WidgetContextMenu: React.FC<IProps> = ({
     onFinished,
     app,
     userWidget,
@@ -158,12 +161,17 @@ const WidgetContextMenu: React.FC<IProps> = ({
     const isLocalWidget = WidgetType.JITSI.matches(app.type);
     let revokeButton;
     if (!userWidget && !isLocalWidget && isAllowedWidget) {
+        const opts: ApprovalOpts = { approved: undefined };
+        ModuleRunner.instance.invoke(WidgetLifecycle.PreLoadRequest, opts, new ElementWidget(app));
+
+        if (!opts.approved) {
             const onRevokeClick = (): void => {
                 logger.info("Revoking permission for widget to load: " + app.eventId);
                 const current = SettingsStore.getValue("allowedWidgets", roomId);
                 if (app.eventId !== undefined) current[app.eventId] = false;
                 const level = SettingsStore.firstSupportedLevel("allowedWidgets");
-            SettingsStore.setValue("allowedWidgets", roomId, level, current).catch((err) => {
+                if (!level) throw new Error("level must be defined");
+                SettingsStore.setValue("allowedWidgets", roomId ?? null, level, current).catch((err) => {
                     logger.error(err);
                     // We don't really need to do anything about this - the user will just hit the button again.
                 });
@@ -172,10 +180,12 @@ const WidgetContextMenu: React.FC<IProps> = ({
 
             revokeButton = <IconizedContextMenuOption onClick={onRevokeClick} label={_t("Revoke permissions")} />;
         }
+    }
 
     let moveLeftButton;
     if (showUnpin && widgetIndex > 0) {
         const onClick = (): void => {
+            if (!room) throw new Error("room must be defined");
             WidgetLayoutStore.instance.moveWithinContainer(room, Container.Top, app, -1);
             onFinished();
         };
@@ -207,5 +217,3 @@ const WidgetContextMenu: React.FC<IProps> = ({
         </IconizedContextMenu>
     );
 };
-
-export default WidgetContextMenu;

src/components/views/dialogs/AskInviteAnywayDialog.tsx

@@ -1,5 +1,6 @@
 /*
 Copyright 2019 New Vector Ltd
+Copyright 2023 The Matrix.org Foundation C.I.C.
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
@@ -14,14 +15,14 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import React from "react";
+import React, { useCallback } from "react";
 
 import { _t } from "../../../languageHandler";
 import SettingsStore from "../../../settings/SettingsStore";
 import { SettingLevel } from "../../../settings/SettingLevel";
 import BaseDialog from "./BaseDialog";
 
-interface IProps {
+export interface AskInviteAnywayDialogProps {
     unknownProfileUsers: Array<{
         userId: string;
         errorText: string;
@@ -31,25 +32,29 @@ interface IProps {
     onFinished: (success: boolean) => void;
 }
 
-export default class AskInviteAnywayDialog extends React.Component<IProps> {
+export default function AskInviteAnywayDialog({
-    private onInviteClicked = (): void => {
+    onFinished,
-        this.props.onInviteAnyways();
+    onGiveUp,
-        this.props.onFinished(true);
+    onInviteAnyways,
-    };
+    unknownProfileUsers,
+}: AskInviteAnywayDialogProps): JSX.Element {
+    const onInviteClicked = useCallback((): void => {
+        onInviteAnyways();
+        onFinished(true);
+    }, [onInviteAnyways, onFinished]);
 
-    private onInviteNeverWarnClicked = (): void => {
+    const onInviteNeverWarnClicked = useCallback((): void => {
         SettingsStore.setValue("promptBeforeInviteUnknownUsers", null, SettingLevel.ACCOUNT, false);
-        this.props.onInviteAnyways();
+        onInviteAnyways();
-        this.props.onFinished(true);
+        onFinished(true);
-    };
+    }, [onInviteAnyways, onFinished]);
 
-    private onGiveUpClicked = (): void => {
+    const onGiveUpClicked = useCallback((): void => {
-        this.props.onGiveUp();
+        onGiveUp();
-        this.props.onFinished(false);
+        onFinished(false);
-    };
+    }, [onGiveUp, onFinished]);
 
-    public render(): React.ReactNode {
+    const errorList = unknownProfileUsers.map((address) => (
-        const errorList = this.props.unknownProfileUsers.map((address) => (
         <li key={address.userId}>
             {address.userId}: {address.errorText}
         </li>
@@ -58,7 +63,7 @@ export default class AskInviteAnywayDialog extends React.Component<IProps> {
     return (
         <BaseDialog
             className="mx_RetryInvitesDialog"
-                onFinished={this.onGiveUpClicked}
+            onFinished={onGiveUpClicked}
             title={_t("The following users may not exist")}
             contentId="mx_Dialog_content"
         >
@@ -73,15 +78,12 @@ export default class AskInviteAnywayDialog extends React.Component<IProps> {
             </div>
 
             <div className="mx_Dialog_buttons">
-                    <button onClick={this.onGiveUpClicked}>{_t("Close")}</button>
+                <button onClick={onGiveUpClicked}>{_t("Close")}</button>
-                    <button onClick={this.onInviteNeverWarnClicked}>
+                <button onClick={onInviteNeverWarnClicked}>{_t("Invite anyway and never warn me again")}</button>
-                        {_t("Invite anyway and never warn me again")}
+                <button onClick={onInviteClicked} autoFocus={true}>
-                    </button>
-                    <button onClick={this.onInviteClicked} autoFocus={true}>
                     {_t("Invite anyway")}
                 </button>
             </div>
         </BaseDialog>
     );
 }
-}

src/components/views/dialogs/LogoutDialog.tsx

@@ -36,7 +36,7 @@ interface IProps {
 interface IState {
     shouldLoadBackupStatus: boolean;
     loading: boolean;
-    backupInfo: IKeyBackupInfo;
+    backupInfo: IKeyBackupInfo | null;
     error?: string;
 }
 
@@ -55,7 +55,6 @@ export default class LogoutDialog extends React.Component<IProps, IState> {
             shouldLoadBackupStatus: shouldLoadBackupStatus,
             loading: shouldLoadBackupStatus,
             backupInfo: null,
-            error: null,
         };
 
         if (shouldLoadBackupStatus) {
@@ -103,14 +102,20 @@ export default class LogoutDialog extends React.Component<IProps, IState> {
             // A key backup exists for this account, but the creating device is not
             // verified, so restore the backup which will give us the keys from it and
             // allow us to trust it (ie. upload keys to it)
-            Modal.createDialog(RestoreKeyBackupDialog, null, null, /* priority = */ false, /* static = */ true);
+            Modal.createDialog(
+                RestoreKeyBackupDialog,
+                undefined,
+                undefined,
+                /* priority = */ false,
+                /* static = */ true,
+            );
         } else {
             Modal.createDialogAsync(
                 import("../../../async-components/views/dialogs/security/CreateKeyBackupDialog") as unknown as Promise<
                     ComponentType<{}>
                 >,
-                null,
+                undefined,
-                null,
+                undefined,
                 /* priority = */ false,
                 /* static = */ true,
             );

src/components/views/dialogs/devtools/RoomNotifications.tsx

@@ -20,7 +20,7 @@ import React, { useContext } from "react";
 
 import MatrixClientContext from "../../../../contexts/MatrixClientContext";
 import { useNotificationState } from "../../../../hooks/useRoomNotificationState";
-import { _t } from "../../../../languageHandler";
+import { _t, _td } from "../../../../languageHandler";
 import { determineUnreadState } from "../../../../RoomNotifs";
 import { humanReadableNotificationColor } from "../../../../stores/notifications/NotificationColor";
 import { doesRoomOrThreadHaveUnreadMessages } from "../../../../Unread";
@@ -39,22 +39,38 @@ export default function RoomNotifications({ onBack }: IDevtoolsProps): JSX.Eleme
                 <h2>{_t("Room status")}</h2>
                 <ul>
                     <li>
-                        {_t("Room unread status: ")}
+                        {_t(
-                        <strong>{humanReadableNotificationColor(color)}</strong>
+                            "Room unread status: <strong>%(status)s</strong>, count: <strong>%(count)s</strong>",
-                        {count > 0 && (
+                            {
-                            <>
+                                status: humanReadableNotificationColor(color),
-                                {_t(", count:")} <strong>{count}</strong>
+                                count,
-                            </>
+                            },
+                            {
+                                strong: (sub) => <strong>{sub}</strong>,
+                            },
                         )}
                     </li>
                     <li>
-                        {_t("Notification state is")} <strong>{notificationState}</strong>
+                        {_t(
+                            "Notification state is <strong>%(notificationState)s</strong>",
+                            {
+                                notificationState,
+                            },
+                            {
+                                strong: (sub) => <strong>{sub}</strong>,
+                            },
+                        )}
                     </li>
                     <li>
-                        {_t("Room is ")}
+                        {_t(
-                        <strong>
+                            cli.isRoomEncrypted(room.roomId!)
-                            {cli.isRoomEncrypted(room.roomId!) ? _t("encrypted ✅") : _t("not encrypted 🚨")}
+                                ? _td("Room is <strong>encrypted ✅</strong>")
-                        </strong>
+                                : _td("Room is <strong>not encrypted 🚨</strong>"),
+                            {},
+                            {
+                                strong: (sub) => <strong>{sub}</strong>,
+                            },
+                        )}
                     </li>
                 </ul>
             </section>

src/components/views/dialogs/polls/PollHistoryDialog.tsx

@@ -14,7 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import React, { useEffect, useState } from "react";
+import React, { useState } from "react";
 import { MatrixClient } from "matrix-js-sdk/src/client";
 import { MatrixEvent, Poll } from "matrix-js-sdk/src/matrix";
 
@@ -23,7 +23,8 @@ import BaseDialog from "../BaseDialog";
 import { IDialogProps } from "../IDialogProps";
 import { PollHistoryList } from "./PollHistoryList";
 import { PollHistoryFilter } from "./types";
-import { usePolls } from "./usePollHistory";
+import { usePollsWithRelations } from "./usePollHistory";
+import { useFetchPastPolls } from "./fetchPastPolls";
 
 type PollHistoryDialogProps = Pick<IDialogProps, "onFinished"> & {
     roomId: string;
@@ -34,7 +35,10 @@ const sortEventsByLatest = (left: MatrixEvent, right: MatrixEvent): number => ri
 const filterPolls =
     (filter: PollHistoryFilter) =>
     (poll: Poll): boolean =>
-        (filter === "ACTIVE") !== poll.isEnded;
+        // exclude polls while they are still loading
+        // to avoid jitter in list
+        !poll.isFetchingResponses && (filter === "ACTIVE") !== poll.isEnded;
+
 const filterAndSortPolls = (polls: Map<string, Poll>, filter: PollHistoryFilter): MatrixEvent[] => {
     return [...polls.values()]
         .filter(filterPolls(filter))
@@ -43,18 +47,24 @@ const filterAndSortPolls = (polls: Map<string, Poll>, filter: PollHistoryFilter)
 };
 
 export const PollHistoryDialog: React.FC<PollHistoryDialogProps> = ({ roomId, matrixClient, onFinished }) => {
-    const { polls } = usePolls(roomId, matrixClient);
+    const room = matrixClient.getRoom(roomId)!;
+    const { isLoading } = useFetchPastPolls(room, matrixClient);
+    const { polls } = usePollsWithRelations(roomId, matrixClient);
     const [filter, setFilter] = useState<PollHistoryFilter>("ACTIVE");
-    const [pollStartEvents, setPollStartEvents] = useState(filterAndSortPolls(polls, filter));
 
-    useEffect(() => {
+    const pollStartEvents = filterAndSortPolls(polls, filter);
-        setPollStartEvents(filterAndSortPolls(polls, filter));
+    const isLoadingPollResponses = [...polls.values()].some((poll) => poll.isFetchingResponses);
-    }, [filter, polls]);
 
     return (
         <BaseDialog title={_t("Polls history")} onFinished={onFinished}>
             <div className="mx_PollHistoryDialog_content">
-                <PollHistoryList pollStartEvents={pollStartEvents} filter={filter} onFilterChange={setFilter} />
+                <PollHistoryList
+                    pollStartEvents={pollStartEvents}
+                    isLoading={isLoading || isLoadingPollResponses}
+                    polls={polls}
+                    filter={filter}
+                    onFilterChange={setFilter}
+                />
             </div>
         </BaseDialog>
     );

src/components/views/dialogs/polls/PollHistoryList.tsx

@@ -15,19 +15,41 @@ limitations under the License.
 */
 
 import React from "react";
-import { MatrixEvent } from "matrix-js-sdk/src/matrix";
+import classNames from "classnames";
+import { MatrixEvent, Poll } from "matrix-js-sdk/src/matrix";
 
-import PollListItem from "./PollListItem";
 import { _t } from "../../../../languageHandler";
 import { FilterTabGroup } from "../../elements/FilterTabGroup";
+import InlineSpinner from "../../elements/InlineSpinner";
 import { PollHistoryFilter } from "./types";
+import { PollListItem } from "./PollListItem";
+import { PollListItemEnded } from "./PollListItemEnded";
+
+const LoadingPolls: React.FC<{ noResultsYet?: boolean }> = ({ noResultsYet }) => (
+    <div
+        className={classNames("mx_PollHistoryList_loading", {
+            mx_PollHistoryList_noResultsYet: noResultsYet,
+        })}
+    >
+        <InlineSpinner />
+        {_t("Loading polls")}
+    </div>
+);
 
 type PollHistoryListProps = {
     pollStartEvents: MatrixEvent[];
+    polls: Map<string, Poll>;
     filter: PollHistoryFilter;
     onFilterChange: (filter: PollHistoryFilter) => void;
+    isLoading?: boolean;
 };
-export const PollHistoryList: React.FC<PollHistoryListProps> = ({ pollStartEvents, filter, onFilterChange }) => {
+export const PollHistoryList: React.FC<PollHistoryListProps> = ({
+    pollStartEvents,
+    polls,
+    filter,
+    isLoading,
+    onFilterChange,
+}) => {
     return (
         <div className="mx_PollHistoryList">
             <FilterTabGroup<PollHistoryFilter>
@@ -39,19 +61,30 @@ export const PollHistoryList: React.FC<PollHistoryListProps> = ({ pollStartEvent
                     { id: "ENDED", label: "Past polls" },
                 ]}
             />
-            {!!pollStartEvents.length ? (
+            {!!pollStartEvents.length && (
-                <ol className="mx_PollHistoryList_list">
+                <ol className={classNames("mx_PollHistoryList_list", `mx_PollHistoryList_list_${filter}`)}>
-                    {pollStartEvents.map((pollStartEvent) => (
+                    {pollStartEvents.map((pollStartEvent) =>
+                        filter === "ACTIVE" ? (
                             <PollListItem key={pollStartEvent.getId()!} event={pollStartEvent} />
-                    ))}
-                </ol>
                         ) : (
+                            <PollListItemEnded
+                                key={pollStartEvent.getId()!}
+                                event={pollStartEvent}
+                                poll={polls.get(pollStartEvent.getId()!)!}
+                            />
+                        ),
+                    )}
+                    {isLoading && <LoadingPolls />}
+                </ol>
+            )}
+            {!pollStartEvents.length && !isLoading && (
                 <span className="mx_PollHistoryList_noResults">
                     {filter === "ACTIVE"
                         ? _t("There are no active polls in this room")
                         : _t("There are no past polls in this room")}
                 </span>
             )}
+            {!pollStartEvents.length && isLoading && <LoadingPolls noResultsYet />}
         </div>
     );
 };

src/components/views/dialogs/polls/PollListItem.tsx

@@ -25,7 +25,7 @@ interface Props {
     event: MatrixEvent;
 }
 
-const PollListItem: React.FC<Props> = ({ event }) => {
+export const PollListItem: React.FC<Props> = ({ event }) => {
     const pollEvent = event.unstableExtensibleEvent as unknown as PollStartEvent;
     if (!pollEvent) {
         return null;
@@ -39,5 +39,3 @@ const PollListItem: React.FC<Props> = ({ event }) => {
         </li>
     );
 };
-
-export default PollListItem;

src/components/views/dialogs/polls/PollListItemEnded.tsx

@@ -0,0 +1,127 @@
+/*
+Copyright 2023 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import React, { useEffect, useState } from "react";
+import { PollAnswerSubevent } from "matrix-js-sdk/src/extensible_events_v1/PollStartEvent";
+import { MatrixEvent, Poll, PollEvent } from "matrix-js-sdk/src/matrix";
+import { Relations } from "matrix-js-sdk/src/models/relations";
+
+import { Icon as PollIcon } from "../../../../../res/img/element-icons/room/composer/poll.svg";
+import { _t } from "../../../../languageHandler";
+import { formatLocalDateShort } from "../../../../DateUtils";
+import { allVotes, collectUserVotes, countVotes } from "../../messages/MPollBody";
+import { PollOption } from "../../polls/PollOption";
+import { Caption } from "../../typography/Caption";
+
+interface Props {
+    event: MatrixEvent;
+    poll: Poll;
+}
+
+type EndedPollState = {
+    winningAnswers: {
+        answer: PollAnswerSubevent;
+        voteCount: number;
+    }[];
+    totalVoteCount: number;
+};
+const getWinningAnswers = (poll: Poll, responseRelations: Relations): EndedPollState => {
+    const userVotes = collectUserVotes(allVotes(responseRelations));
+    const votes = countVotes(userVotes, poll.pollEvent);
+    const totalVoteCount = [...votes.values()].reduce((sum, vote) => sum + vote, 0);
+    const winCount = Math.max(...votes.values());
+
+    return {
+        totalVoteCount,
+        winningAnswers: poll.pollEvent.answers
+            .filter((answer) => votes.get(answer.id) === winCount)
+            .map((answer) => ({
+                answer,
+                voteCount: votes.get(answer.id) || 0,
+            })),
+    };
+};
+
+/**
+ * Get deduplicated and validated poll responses
+ * Will use cached responses from Poll instance when existing
+ * Updates on changes to Poll responses (paging relations or from sync)
+ * Returns winning answers and total vote count
+ */
+const usePollVotes = (poll: Poll): Partial<EndedPollState> => {
+    const [results, setResults] = useState({ totalVoteCount: 0 });
+
+    useEffect(() => {
+        const getResponses = async (): Promise<void> => {
+            const responseRelations = await poll.getResponses();
+            setResults(getWinningAnswers(poll, responseRelations));
+        };
+        const onPollResponses = (responseRelations: Relations): void =>
+            setResults(getWinningAnswers(poll, responseRelations));
+        poll.on(PollEvent.Responses, onPollResponses);
+
+        getResponses();
+
+        return () => {
+            poll.off(PollEvent.Responses, onPollResponses);
+        };
+    }, [poll]);
+
+    return results;
+};
+
+/**
+ * Render an ended poll with the winning answer and vote count
+ * @param event - the poll start MatrixEvent
+ * @param poll - Poll instance
+ */
+export const PollListItemEnded: React.FC<Props> = ({ event, poll }) => {
+    const pollEvent = poll.pollEvent;
+    const { winningAnswers, totalVoteCount } = usePollVotes(poll);
+    if (!pollEvent) {
+        return null;
+    }
+    const formattedDate = formatLocalDateShort(event.getTs());
+
+    return (
+        <li data-testid={`pollListItem-${event.getId()!}`} className="mx_PollListItemEnded">
+            <div className="mx_PollListItemEnded_title">
+                <PollIcon className="mx_PollListItemEnded_icon" />
+                <span className="mx_PollListItemEnded_question">{pollEvent.question.text}</span>
+                <Caption>{formattedDate}</Caption>
+            </div>
+            {!!winningAnswers?.length && (
+                <div className="mx_PollListItemEnded_answers">
+                    {winningAnswers?.map(({ answer, voteCount }) => (
+                        <PollOption
+                            key={answer.id}
+                            answer={answer}
+                            voteCount={voteCount}
+                            totalVoteCount={totalVoteCount!}
+                            pollId={poll.pollId}
+                            displayVoteCount
+                            isChecked
+                            isEnded
+                        />
+                    ))}
+                </div>
+            )}
+            <div className="mx_PollListItemEnded_voteCount">
+                <Caption>{_t("Final result based on %(count)s votes", { count: totalVoteCount })}</Caption>
+            </div>
+        </li>
+    );
+};

src/components/views/dialogs/polls/fetchPastPolls.ts

@@ -0,0 +1,129 @@
+/*
+Copyright 2023 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import { useEffect, useState } from "react";
+import { M_POLL_START } from "matrix-js-sdk/src/@types/polls";
+import { MatrixClient } from "matrix-js-sdk/src/client";
+import { EventTimeline, EventTimelineSet, Room } from "matrix-js-sdk/src/matrix";
+import { Filter, IFilterDefinition } from "matrix-js-sdk/src/filter";
+import { logger } from "matrix-js-sdk/src/logger";
+
+/**
+ * Page timeline backwards until either:
+ * - event older than endOfHistoryPeriodTimestamp is encountered
+ * - end of timeline is reached
+ * @param timelineSet - timelineset to page
+ * @param matrixClient - client
+ * @param endOfHistoryPeriodTimestamp - epoch timestamp to fetch until
+ * @returns void
+ */
+const pagePolls = async (
+    timelineSet: EventTimelineSet,
+    matrixClient: MatrixClient,
+    endOfHistoryPeriodTimestamp: number,
+): Promise<void> => {
+    const liveTimeline = timelineSet.getLiveTimeline();
+    const events = liveTimeline.getEvents();
+    const oldestEventTimestamp = events[0]?.getTs() || Date.now();
+    const hasMorePages = !!liveTimeline.getPaginationToken(EventTimeline.BACKWARDS);
+
+    if (!hasMorePages || oldestEventTimestamp <= endOfHistoryPeriodTimestamp) {
+        return;
+    }
+
+    await matrixClient.paginateEventTimeline(liveTimeline, {
+        backwards: true,
+    });
+
+    return pagePolls(timelineSet, matrixClient, endOfHistoryPeriodTimestamp);
+};
+
+const ONE_DAY_MS = 60000 * 60 * 24;
+/**
+ * Fetches timeline history for given number of days in past
+ * @param timelineSet - timelineset to page
+ * @param matrixClient - client
+ * @param historyPeriodDays - number of days of history to fetch, from current day
+ * @returns isLoading - true while fetching history
+ */
+const useTimelineHistory = (
+    timelineSet: EventTimelineSet | null,
+    matrixClient: MatrixClient,
+    historyPeriodDays: number,
+): { isLoading: boolean } => {
+    const [isLoading, setIsLoading] = useState(true);
+
+    useEffect(() => {
+        if (!timelineSet) {
+            return;
+        }
+        const endOfHistoryPeriodTimestamp = Date.now() - ONE_DAY_MS * historyPeriodDays;
+
+        const doFetchHistory = async (): Promise<void> => {
+            setIsLoading(true);
+            try {
+                await pagePolls(timelineSet, matrixClient, endOfHistoryPeriodTimestamp);
+            } catch (error) {
+                logger.error("Failed to fetch room polls history", error);
+            } finally {
+                setIsLoading(false);
+            }
+        };
+        doFetchHistory();
+    }, [timelineSet, historyPeriodDays, matrixClient]);
+
+    return { isLoading };
+};
+
+const filterDefinition: IFilterDefinition = {
+    room: {
+        timeline: {
+            types: [M_POLL_START.name, M_POLL_START.altName],
+        },
+    },
+};
+
+/**
+ * Fetch poll start events in the last N days of room history
+ * @param room - room to fetch history for
+ * @param matrixClient - client
+ * @param historyPeriodDays - number of days of history to fetch, from current day
+ * @returns isLoading - true while fetching history
+ */
+export const useFetchPastPolls = (
+    room: Room,
+    matrixClient: MatrixClient,
+    historyPeriodDays = 30,
+): { isLoading: boolean } => {
+    const [timelineSet, setTimelineSet] = useState<EventTimelineSet | null>(null);
+
+    useEffect(() => {
+        const filter = new Filter(matrixClient.getSafeUserId());
+        filter.setDefinition(filterDefinition);
+        const getFilteredTimelineSet = async (): Promise<void> => {
+            const filterId = await matrixClient.getOrCreateFilter(`POLL_HISTORY_FILTER_${room.roomId}}`, filter);
+            filter.filterId = filterId;
+            const timelineSet = room.getOrCreateFilteredTimelineSet(filter);
+            setTimelineSet(timelineSet);
+        };
+
+        getFilteredTimelineSet();
+    }, [room, matrixClient]);
+
+    const { isLoading } = useTimelineHistory(timelineSet, matrixClient, historyPeriodDays);
+
+    return { isLoading };
+};

src/components/views/dialogs/polls/usePollHistory.ts

@@ -14,6 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
+import { useEffect, useState } from "react";
 import { Poll, PollEvent } from "matrix-js-sdk/src/matrix";
 import { MatrixClient } from "matrix-js-sdk/src/client";
 
@@ -21,6 +22,7 @@ import { useEventEmitterState } from "../../../../hooks/useEventEmitter";
 
 /**
  * Get poll instances from a room
+ * Updates to include new polls
  * @param roomId - id of room to retrieve polls for
  * @param matrixClient - client
  * @returns {Map<string, Poll>} - Map of Poll instances
@@ -37,9 +39,58 @@ export const usePolls = (
         throw new Error("Cannot find room");
     }
 
-    const polls = useEventEmitterState(room, PollEvent.New, () => room.polls);
+    // copy room.polls map so changes can be detected
-
+    const polls = useEventEmitterState(room, PollEvent.New, () => new Map<string, Poll>(room.polls));
-    // @TODO(kerrya) watch polls for end events, trigger refiltering
 
     return { polls };
 };
+
+/**
+ * Get all poll instances from a room
+ * Fetch their responses (using cached poll responses)
+ * Updates on:
+ * - new polls added to room
+ * - new responses added to polls
+ * - changes to poll ended state
+ * @param roomId - id of room to retrieve polls for
+ * @param matrixClient - client
+ * @returns {Map<string, Poll>} - Map of Poll instances
+ */
+export const usePollsWithRelations = (
+    roomId: string,
+    matrixClient: MatrixClient,
+): {
+    polls: Map<string, Poll>;
+} => {
+    const { polls } = usePolls(roomId, matrixClient);
+    const [pollsWithRelations, setPollsWithRelations] = useState<Map<string, Poll>>(polls);
+
+    useEffect(() => {
+        const onPollUpdate = async (): Promise<void> => {
+            // trigger rerender by creating a new poll map
+            setPollsWithRelations(new Map(polls));
+        };
+        if (polls) {
+            for (const poll of polls.values()) {
+                // listen to changes in responses and end state
+                poll.on(PollEvent.End, onPollUpdate);
+                poll.on(PollEvent.Responses, onPollUpdate);
+                // trigger request to get all responses
+                // if they are not already in cache
+                poll.getResponses();
+            }
+            setPollsWithRelations(polls);
+        }
+        // unsubscribe
+        return () => {
+            if (polls) {
+                for (const poll of polls.values()) {
+                    poll.off(PollEvent.End, onPollUpdate);
+                    poll.off(PollEvent.Responses, onPollUpdate);
+                }
+            }
+        };
+    }, [polls, setPollsWithRelations]);
+
+    return { polls: pollsWithRelations };
+};

src/components/views/dialogs/spotlight/SpotlightDialog.tsx

@@ -93,6 +93,7 @@ import { isLocalRoom } from "../../../../utils/localRoom/isLocalRoom";
 import { shouldShowFeedback } from "../../../../utils/Feedback";
 import RoomAvatar from "../../avatars/RoomAvatar";
 import { useFeatureEnabled } from "../../../../hooks/useSettings";
+import { filterBoolean } from "../../../../utils/arrays";
 
 const MAX_RECENT_SEARCHES = 10;
 const SECTION_LIMIT = 50; // only show 50 results per section for performance reasons
@@ -173,13 +174,13 @@ const toPublicRoomResult = (publicRoom: IPublicRoomsChunkRoom): IPublicRoomResul
     publicRoom,
     section: Section.PublicRooms,
     filter: [Filter.PublicRooms],
-    query: [
+    query: filterBoolean([
         publicRoom.room_id.toLowerCase(),
         publicRoom.canonical_alias?.toLowerCase(),
         publicRoom.name?.toLowerCase(),
         sanitizeHtml(publicRoom.topic?.toLowerCase() ?? "", { allowedTags: [] }),
         ...(publicRoom.aliases?.map((it) => it.toLowerCase()) || []),
-    ].filter(Boolean) as string[],
+    ]),
 });
 
 const toRoomResult = (room: Room): IRoomResult => {

src/components/views/elements/AppTile.tsx

@@ -23,6 +23,7 @@ import classNames from "classnames";
 import { MatrixCapabilities } from "matrix-widget-api";
 import { Room, RoomEvent } from "matrix-js-sdk/src/models/room";
 import { logger } from "matrix-js-sdk/src/logger";
+import { ApprovalOpts, WidgetLifecycle } from "@matrix-org/react-sdk-module-api/lib/lifecycles/WidgetLifecycle";
 
 import AccessibleButton from "./AccessibleButton";
 import { _t } from "../../../languageHandler";
@@ -36,7 +37,7 @@ import { aboveLeftOf, ContextMenuButton } from "../../structures/ContextMenu";
 import PersistedElement, { getPersistKey } from "./PersistedElement";
 import { WidgetType } from "../../../widgets/WidgetType";
 import { ElementWidget, StopGapWidget } from "../../../stores/widgets/StopGapWidget";
-import WidgetContextMenu from "../context_menus/WidgetContextMenu";
+import { WidgetContextMenu } from "../context_menus/WidgetContextMenu";
 import WidgetAvatar from "../avatars/WidgetAvatar";
 import LegacyCallHandler from "../../../LegacyCallHandler";
 import { IApp } from "../../../stores/WidgetStore";
@@ -50,6 +51,7 @@ import { Action } from "../../../dispatcher/actions";
 import { ElementWidgetCapabilities } from "../../../stores/widgets/ElementWidgetCapabilities";
 import { WidgetMessagingStore } from "../../../stores/widgets/WidgetMessagingStore";
 import { SdkContextClass } from "../../../contexts/SDKContext";
+import { ModuleRunner } from "../../../modules/ModuleRunner";
 
 interface IProps {
     app: IApp;
@@ -162,6 +164,9 @@ export default class AppTile extends React.Component<IProps, IState> {
     private hasPermissionToLoad = (props: IProps): boolean => {
         if (this.usingLocalWidget()) return true;
         if (!props.room) return true; // user widgets always have permissions
+        const opts: ApprovalOpts = { approved: undefined };
+        ModuleRunner.instance.invoke(WidgetLifecycle.PreLoadRequest, opts, new ElementWidget(this.props.app));
+        if (opts.approved) return true;
 
         const currentlyAllowedWidgets = SettingsStore.getValue("allowedWidgets", props.room.roomId);
         const allowed = props.app.eventId !== undefined && (currentlyAllowedWidgets[props.app.eventId] ?? false);

src/components/views/elements/EditableTextContainer.tsx

@@ -32,7 +32,7 @@ interface IProps {
 
     /* callback to update the value. Called with a single argument: the new
      * value. */
-    onSubmit?: (value: string) => Promise<{} | void>;
+    onSubmit: (value: string) => Promise<{} | void>;
 
     /* should the input submit when focus is lost? */
     blurToSubmit?: boolean;
@@ -40,7 +40,7 @@ interface IProps {
 
 interface IState {
     busy: boolean;
-    errorString: string;
+    errorString: string | null;
     value: string;
 }
 
@@ -72,7 +72,7 @@ export default class EditableTextContainer extends React.Component<IProps, IStat
         this.state = {
             busy: false,
             errorString: null,
-            value: props.initialValue,
+            value: props.initialValue ?? "",
         };
     }
 

src/components/views/elements/SSOButtons.tsx

@@ -113,7 +113,7 @@ const SSOButton: React.FC<ISSOButtonProps> = ({
         brandClass = `mx_SSOButton_brand_${brandName}`;
         icon = <img src={brandIcon} height="24" width="24" alt={brandName} />;
     } else if (typeof idp?.icon === "string" && idp.icon.startsWith("mxc://")) {
-        const src = mediaFromMxc(idp.icon, matrixClient).getSquareThumbnailHttp(24);
+        const src = mediaFromMxc(idp.icon, matrixClient).getSquareThumbnailHttp(24) ?? undefined;
         icon = <img src={src} height="24" width="24" alt={idp.name} />;
     }
 

src/components/views/elements/SearchWarning.tsx

@@ -14,7 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import React from "react";
+import React, { ReactNode } from "react";
 import { logger } from "matrix-js-sdk/src/logger";
 
 import EventIndexPeg from "../../../indexing/EventIndexPeg";
@@ -31,13 +31,13 @@ export enum WarningKind {
 }
 
 interface IProps {
-    isRoomEncrypted: boolean;
+    isRoomEncrypted?: boolean;
     kind: WarningKind;
 }
 
 export default function SearchWarning({ isRoomEncrypted, kind }: IProps): JSX.Element {
-    if (!isRoomEncrypted) return null;
+    if (!isRoomEncrypted) return <></>;
-    if (EventIndexPeg.get()) return null;
+    if (EventIndexPeg.get()) return <></>;
 
     if (EventIndexPeg.error) {
         return (
@@ -69,8 +69,8 @@ export default function SearchWarning({ isRoomEncrypted, kind }: IProps): JSX.El
     const brand = SdkConfig.get("brand");
     const desktopBuilds = SdkConfig.getObject("desktop_builds");
 
-    let text = null;
+    let text: ReactNode | undefined;
-    let logo = null;
+    let logo: JSX.Element | undefined;
     if (desktopBuilds.get("available")) {
         logo = <img src={desktopBuilds.get("logo")} />;
         const buildUrl = desktopBuilds.get("url");
@@ -116,7 +116,7 @@ export default function SearchWarning({ isRoomEncrypted, kind }: IProps): JSX.El
     // for safety
     if (!text) {
         logger.warn("Unknown desktop builds warning kind: ", kind);
-        return null;
+        return <></>;
     }
 
     return (

src/components/views/elements/Validation.tsx

@@ -26,7 +26,7 @@ interface IResult {
     text: string;
 }
 
-interface IRule<T, D = void> {
+interface IRule<T, D = undefined> {
     key: string;
     final?: boolean;
     skip?(this: T, data: Data, derivedData: D): boolean;
@@ -90,14 +90,12 @@ export default function withValidation<T = void, D = void>({
         { value, focused, allowEmpty = true }: IFieldState,
     ): Promise<IValidationResult> {
         if (!value && allowEmpty) {
-            return {
+            return {};
-                valid: null,
-                feedback: null,
-            };
         }
 
         const data = { value, allowEmpty };
-        const derivedData: D | undefined = deriveData ? await deriveData.call(this, data) : undefined;
+        // We know that if deriveData is set then D will not be undefined
+        const derivedData: D = (await deriveData?.call(this, data)) as D;
 
         const results: IResult[] = [];
         let valid = true;
@@ -149,10 +147,7 @@ export default function withValidation<T = void, D = void>({
 
         // Hide feedback when not focused
         if (!focused) {
-            return {
+            return { valid };
-                valid,
-                feedback: null,
-            };
         }
 
         let details;

src/components/views/emojipicker/Category.tsx

@@ -38,7 +38,7 @@ interface IProps {
     id: string;
     name: string;
     emojis: IEmoji[];
-    selectedEmojis: Set<string>;
+    selectedEmojis?: Set<string>;
     heightBefore: number;
     viewportHeight: number;
     scrollTop: number;

src/components/views/emojipicker/EmojiPicker.tsx

@@ -26,6 +26,7 @@ import Search from "./Search";
 import Preview from "./Preview";
 import QuickReactions from "./QuickReactions";
 import Category, { ICategory, CategoryKey } from "./Category";
+import { filterBoolean } from "../../../utils/arrays";
 
 export const CATEGORY_HEADER_HEIGHT = 20;
 export const EMOJI_HEIGHT = 35;
@@ -62,13 +63,12 @@ class EmojiPicker extends React.Component<IProps, IState> {
 
         this.state = {
             filter: "",
-            previewEmoji: null,
             scrollTop: 0,
             viewportHeight: 280,
         };
 
         // Convert recent emoji characters to emoji data, removing unknowns and duplicates
-        this.recentlyUsed = Array.from(new Set(recent.get().map(getEmojiFromUnicode).filter(Boolean)));
+        this.recentlyUsed = Array.from(new Set(filterBoolean(recent.get().map(getEmojiFromUnicode))));
         this.memoizedDataByCategory = {
             recent: this.recentlyUsed,
             ...DATA_BY_CATEGORY,
@@ -230,9 +230,9 @@ class EmojiPicker extends React.Component<IProps, IState> {
         });
     };
 
-    private onHoverEmojiEnd = (emoji: IEmoji): void => {
+    private onHoverEmojiEnd = (): void => {
         this.setState({
-            previewEmoji: null,
+            previewEmoji: undefined,
         });
     };
 

src/components/views/emojipicker/QuickReactions.tsx

@@ -42,9 +42,7 @@ interface IState {
 class QuickReactions extends React.Component<IProps, IState> {
     public constructor(props: IProps) {
         super(props);
-        this.state = {
+        this.state = {};
-            hover: null,
-        };
     }
 
     private onMouseEnter = (emoji: IEmoji): void => {
@@ -55,7 +53,7 @@ class QuickReactions extends React.Component<IProps, IState> {
 
     private onMouseLeave = (): void => {
         this.setState({
-            hover: null,
+            hover: undefined,
         });
     };
 

src/components/views/emojipicker/ReactionPicker.tsx

@@ -77,8 +77,8 @@ class ReactionPicker extends React.Component<IProps, IState> {
         if (!this.props.reactions) {
             return {};
         }
-        const userId = MatrixClientPeg.get().getUserId();
+        const userId = MatrixClientPeg.get().getUserId()!;
-        const myAnnotations = this.props.reactions.getAnnotationsBySender()[userId] || new Set<MatrixEvent>();
+        const myAnnotations = this.props.reactions.getAnnotationsBySender()?.[userId] ?? new Set<MatrixEvent>();
         return Object.fromEntries(
             [...myAnnotations]
                 .filter((event) => !event.isRedacted())
@@ -97,9 +97,9 @@ class ReactionPicker extends React.Component<IProps, IState> {
         this.props.onFinished();
         const myReactions = this.getReactions();
         if (myReactions.hasOwnProperty(reaction)) {
-            if (this.props.mxEvent.isRedacted() || !this.context.canSelfRedact) return;
+            if (this.props.mxEvent.isRedacted() || !this.context.canSelfRedact) return false;
 
-            MatrixClientPeg.get().redactEvent(this.props.mxEvent.getRoomId(), myReactions[reaction]);
+            MatrixClientPeg.get().redactEvent(this.props.mxEvent.getRoomId()!, myReactions[reaction]);
             dis.dispatch<FocusComposerPayload>({
                 action: Action.FocusAComposer,
                 context: this.context.timelineRenderingType,
@@ -107,7 +107,7 @@ class ReactionPicker extends React.Component<IProps, IState> {
             // Tell the emoji picker not to bump this in the more frequently used list.
             return false;
         } else {
-            MatrixClientPeg.get().sendEvent(this.props.mxEvent.getRoomId(), EventType.Reaction, {
+            MatrixClientPeg.get().sendEvent(this.props.mxEvent.getRoomId()!, EventType.Reaction, {
                 "m.relates_to": {
                     rel_type: RelationType.Annotation,
                     event_id: this.props.mxEvent.getId(),

src/components/views/emojipicker/Search.tsx

@@ -32,7 +32,7 @@ class Search extends React.PureComponent<IProps> {
 
     public componentDidMount(): void {
         // For some reason, neither the autoFocus nor just calling focus() here worked, so here's a window.setTimeout
-        window.setTimeout(() => this.inputRef.current.focus(), 0);
+        window.setTimeout(() => this.inputRef.current?.focus(), 0);
     }
 
     private onKeyDown = (ev: React.KeyboardEvent): void => {

src/components/views/location/EnableLiveShare.tsx

@@ -29,7 +29,7 @@ interface Props {
 export const EnableLiveShare: React.FC<Props> = ({ onSubmit }) => {
     const [isEnabled, setEnabled] = useState(false);
     return (
-        <div data-test-id="location-picker-enable-live-share" className="mx_EnableLiveShare">
+        <div data-testid="location-picker-enable-live-share" className="mx_EnableLiveShare">
             <StyledLiveBeaconIcon className="mx_EnableLiveShare_icon" />
             <Heading className="mx_EnableLiveShare_heading" size="h3">
                 {_t("Live location sharing")}
@@ -43,13 +43,13 @@ export const EnableLiveShare: React.FC<Props> = ({ onSubmit }) => {
                 )}
             </p>
             <LabelledToggleSwitch
-                data-test-id="enable-live-share-toggle"
+                data-testid="enable-live-share-toggle"
                 value={isEnabled}
                 onChange={setEnabled}
                 label={_t("Enable live location sharing")}
             />
             <AccessibleButton
-                data-test-id="enable-live-share-submit"
+                data-testid="enable-live-share-submit"
                 className="mx_EnableLiveShare_button"
                 element="button"
                 kind="primary"

src/components/views/location/LiveDurationDropdown.tsx

@@ -62,7 +62,7 @@ const LiveDurationDropdown: React.FC<Props> = ({ timeout, onChange }) => {
     return (
         <Dropdown
             id="live-duration"
-            data-test-id="live-duration-dropdown"
+            data-testid="live-duration-dropdown"
             label={getLabel(timeout)}
             value={timeout.toString()}
             onOptionChange={onOptionChange}

src/components/views/location/LocationPicker.tsx

@@ -231,7 +231,7 @@ class LocationPicker extends React.Component<ILocationPickerProps, IState> {
                             <LiveDurationDropdown onChange={this.onTimeoutChange} timeout={this.state.timeout} />
                         )}
                         <AccessibleButton
-                            data-test-id="location-picker-submit-button"
+                            data-testid="location-picker-submit-button"
                             type="submit"
                             element="button"
                             kind="primary"

src/components/views/location/MapError.tsx

@@ -33,7 +33,7 @@ export interface MapErrorProps {
 
 export const MapError: React.FC<MapErrorProps> = ({ error, isMinimised, className, onFinished, onClick }) => (
     <div
-        data-test-id="map-rendering-error"
+        data-testid="map-rendering-error"
         className={classNames("mx_MapError", className, { mx_MapError_isMinimised: isMinimised })}
         onClick={onClick}
     >

src/components/views/location/ShareDialogButtons.tsx

@@ -19,6 +19,7 @@ import React from "react";
 import AccessibleButton from "../elements/AccessibleButton";
 import { Icon as BackIcon } from "../../../../res/img/element-icons/caret-left.svg";
 import { Icon as CloseIcon } from "../../../../res/img/element-icons/cancel-rounded.svg";
+import { _t } from "../../../languageHandler";
 
 interface Props {
     onCancel: () => void;
@@ -32,7 +33,8 @@ const ShareDialogButtons: React.FC<Props> = ({ onBack, onCancel, displayBack })
             {displayBack && (
                 <AccessibleButton
                     className="mx_ShareDialogButtons_button left"
-                    data-test-id="share-dialog-buttons-back"
+                    data-testid="share-dialog-buttons-back"
+                    aria-label={_t("Back")}
                     onClick={onBack}
                     element="button"
                 >
@@ -41,7 +43,8 @@ const ShareDialogButtons: React.FC<Props> = ({ onBack, onCancel, displayBack })
             )}
             <AccessibleButton
                 className="mx_ShareDialogButtons_button right"
-                data-test-id="share-dialog-buttons-cancel"
+                data-testid="share-dialog-buttons-cancel"
+                aria-label={_t("Close")}
                 onClick={onCancel}
                 element="button"
             >

src/components/views/messages/DateSeparator.tsx

@@ -73,7 +73,7 @@ export default class DateSeparator extends React.Component<IProps, IState> {
     }
 
     public componentWillUnmount(): void {
-        SettingsStore.unwatchSetting(this.settingWatcherRef);
+        if (this.settingWatcherRef) SettingsStore.unwatchSetting(this.settingWatcherRef);
     }
 
     private onContextMenuOpenClick = (e: React.MouseEvent): void => {
@@ -89,7 +89,7 @@ export default class DateSeparator extends React.Component<IProps, IState> {
 
     private closeMenu = (): void => {
         this.setState({
-            contextMenuPosition: null,
+            contextMenuPosition: undefined,
         });
     };
 
@@ -181,7 +181,7 @@ export default class DateSeparator extends React.Component<IProps, IState> {
     };
 
     private renderJumpToDateMenu(): React.ReactElement {
-        let contextMenu: JSX.Element;
+        let contextMenu: JSX.Element | undefined;
         if (this.state.contextMenuPosition) {
             contextMenu = (
                 <IconizedContextMenu

src/components/views/messages/DecryptionFailureBody.tsx

@@ -14,14 +14,19 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import React, { ReactNode } from "react";
+import React from "react";
+import { MatrixEvent } from "matrix-js-sdk/src/matrix";
 
 import { _t } from "../../../languageHandler";
 import { IBodyProps } from "./IBodyProps";
 
+function getErrorMessage(mxEvent?: MatrixEvent): string {
+    return mxEvent?.isEncryptedDisabledForUnverifiedDevices
+        ? _t("The sender has blocked you from receiving this message")
+        : _t("Unable to decrypt message");
+}
+
 // A placeholder element for messages that could not be decrypted
-export default class DecryptionFailureBody extends React.Component<Partial<IBodyProps>> {
+export function DecryptionFailureBody({ mxEvent }: Partial<IBodyProps>): JSX.Element {
-    public render(): ReactNode {
+    return <div className="mx_DecryptionFailureBody mx_EventTile_content">{getErrorMessage(mxEvent)}</div>;
-        return <div className="mx_DecryptionFailureBody mx_EventTile_content">{_t("Unable to decrypt message")}</div>;
-    }
 }

src/components/views/messages/LegacyCallEvent.tsx

@@ -191,6 +191,13 @@ export default class LegacyCallEvent extends React.PureComponent<IProps, IState>
                         {this.props.timestamp}
                     </div>
                 );
+            } else if (hangupReason === CallErrorCode.AnsweredElsewhere) {
+                return (
+                    <div className="mx_LegacyCallEvent_content">
+                        {_t("Answered elsewhere")}
+                        {this.props.timestamp}
+                    </div>
+                );
             }
 
             let reason;

src/components/views/messages/MPollBody.tsx

@@ -182,12 +182,14 @@ export default class MPollBody extends React.Component<IBodyProps, IState> {
     private addListeners(): void {
         this.state.poll?.on(PollEvent.Responses, this.onResponsesChange);
         this.state.poll?.on(PollEvent.End, this.onRelationsChange);
+        this.state.poll?.on(PollEvent.UndecryptableRelations, this.render.bind(this));
     }
 
     private removeListeners(): void {
         if (this.state.poll) {
             this.state.poll.off(PollEvent.Responses, this.onResponsesChange);
             this.state.poll.off(PollEvent.End, this.onRelationsChange);
+            this.state.poll.off(PollEvent.UndecryptableRelations, this.render.bind(this));
         }
     }
 
@@ -297,7 +299,9 @@ export default class MPollBody extends React.Component<IBodyProps, IState> {
         const showResults = poll.isEnded || (disclosed && myVote !== undefined);
 
         let totalText: string;
-        if (poll.isEnded) {
+        if (showResults && poll.undecryptableRelationsCount) {
+            totalText = _t("Due to decryption errors, some votes may not be counted");
+        } else if (poll.isEnded) {
             totalText = _t("Final result based on %(count)s votes", { count: totalVotes });
         } else if (!disclosed) {
             totalText = _t("Results will be visible when the poll is ended");
@@ -384,7 +388,7 @@ export function allVotes(voteRelations: Relations): Array<UserVote> {
  * @param {string?} selected Local echo selected option for the userId
  * @returns a Map of user ID to their vote info
  */
-function collectUserVotes(
+export function collectUserVotes(
     userResponses: Array<UserVote>,
     userId?: string | null | undefined,
     selected?: string | null | undefined,
@@ -405,7 +409,7 @@ function collectUserVotes(
     return userVotes;
 }
 
-function countVotes(userVotes: Map<string, UserVote>, pollStart: PollStartEvent): Map<string, number> {
+export function countVotes(userVotes: Map<string, UserVote>, pollStart: PollStartEvent): Map<string, number> {
     const collected = new Map<string, number>();
 
     for (const response of userVotes.values()) {

src/components/views/messages/MPollEndBody.tsx

@@ -21,7 +21,9 @@ import { logger } from "matrix-js-sdk/src/logger";
 
 import { Icon as PollIcon } from "../../../../res/img/element-icons/room/composer/poll.svg";
 import MatrixClientContext from "../../../contexts/MatrixClientContext";
+import { _t } from "../../../languageHandler";
 import { textForEvent } from "../../../TextForEvent";
+import { Caption } from "../typography/Caption";
 import { IBodyProps } from "./IBodyProps";
 import MPollBody from "./MPollBody";
 
@@ -105,5 +107,10 @@ export const MPollEndBody = React.forwardRef<any, IBodyProps>(({ mxEvent, ...pro
         );
     }
 
-    return <MPollBody mxEvent={pollStartEvent} {...props} />;
+    return (
+        <div>
+            <Caption>{_t("Ended a poll")}</Caption>
+            <MPollBody mxEvent={pollStartEvent} {...props} />
+        </div>
+    );
 });

src/components/views/messages/MessageEvent.tsx

@@ -41,7 +41,7 @@ import { MPollEndBody } from "./MPollEndBody";
 import MLocationBody from "./MLocationBody";
 import MjolnirBody from "./MjolnirBody";
 import MBeaconBody from "./MBeaconBody";
-import DecryptionFailureBody from "./DecryptionFailureBody";
+import { DecryptionFailureBody } from "./DecryptionFailureBody";
 import { GetRelationsForEvent, IEventTileOps } from "../rooms/EventTile";
 import { VoiceBroadcastBody, VoiceBroadcastInfoEventType, VoiceBroadcastInfoState } from "../../../voice-broadcast";
 

src/components/views/right_panel/RoomSummaryCard.tsx

@@ -40,7 +40,7 @@ import { E2EStatus } from "../../../utils/ShieldUtils";
 import RoomContext from "../../../contexts/RoomContext";
 import { UIComponent, UIFeature } from "../../../settings/UIFeature";
 import { ChevronFace, ContextMenuTooltipButton, useContextMenu } from "../../structures/ContextMenu";
-import WidgetContextMenu from "../context_menus/WidgetContextMenu";
+import { WidgetContextMenu } from "../context_menus/WidgetContextMenu";
 import { useRoomMemberCount } from "../../../hooks/useRoomMembers";
 import { useFeatureEnabled } from "../../../hooks/useSettings";
 import { usePinnedEvents } from "./PinnedMessagesCard";

src/components/views/right_panel/WidgetCard.tsx

@@ -24,7 +24,7 @@ import AppTile from "../elements/AppTile";
 import { _t } from "../../../languageHandler";
 import { useWidgets } from "./RoomSummaryCard";
 import { ChevronFace, ContextMenuButton, useContextMenu } from "../../structures/ContextMenu";
-import WidgetContextMenu from "../context_menus/WidgetContextMenu";
+import { WidgetContextMenu } from "../context_menus/WidgetContextMenu";
 import { Container, WidgetLayoutStore } from "../../../stores/widgets/WidgetLayoutStore";
 import UIStore from "../../../stores/UIStore";
 import RightPanelStore from "../../../stores/right-panel/RightPanelStore";

src/components/views/room_settings/AliasSettings.tsx

@@ -399,7 +399,7 @@ export default class AliasSettings extends React.Component<IProps, IState> {
         return (
             <div className="mx_AliasSettings">
                 <SettingsFieldset
-                    data-test-id="published-address-fieldset"
+                    data-testid="published-address-fieldset"
                     legend={_t("Published Addresses")}
                     description={
                         <>
@@ -450,7 +450,7 @@ export default class AliasSettings extends React.Component<IProps, IState> {
                     />
                 </SettingsFieldset>
                 <SettingsFieldset
-                    data-test-id="local-address-fieldset"
+                    data-testid="local-address-fieldset"
                     legend={_t("Local Addresses")}
                     description={
                         isSpaceRoom

src/components/views/rooms/EventTile.tsx

@@ -35,7 +35,7 @@ import { Layout } from "../../../settings/enums/Layout";
 import { formatTime } from "../../../DateUtils";
 import { MatrixClientPeg } from "../../../MatrixClientPeg";
 import MatrixClientContext from "../../../contexts/MatrixClientContext";
-import DecryptionFailureBody from "../messages/DecryptionFailureBody";
+import { DecryptionFailureBody } from "../messages/DecryptionFailureBody";
 import { E2EState } from "./E2EIcon";
 import RoomAvatar from "../avatars/RoomAvatar";
 import MessageContextMenu from "../context_menus/MessageContextMenu";
@@ -1270,7 +1270,7 @@ export class UnwrappedEventTile extends React.Component<EventTileProps, IState>
                                 {this.props.mxEvent.isRedacted() ? (
                                     <RedactedBody mxEvent={this.props.mxEvent} />
                                 ) : this.props.mxEvent.isDecryptionFailure() ? (
-                                    <DecryptionFailureBody />
+                                    <DecryptionFailureBody mxEvent={this.props.mxEvent} />
                                 ) : (
                                     MessagePreviewStore.instance.generatePreviewForEvent(this.props.mxEvent)
                                 )}

src/components/views/rooms/ExtraTile.tsx

@@ -1,5 +1,5 @@
 /*
-Copyright 2020, 2021 The Matrix.org Foundation C.I.C.
+Copyright 2020 - 2023 The Matrix.org Foundation C.I.C.
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
@@ -21,8 +21,9 @@ import { RovingAccessibleButton, RovingAccessibleTooltipButton } from "../../../
 import NotificationBadge from "./NotificationBadge";
 import { NotificationState } from "../../../stores/notifications/NotificationState";
 import { ButtonEvent } from "../elements/AccessibleButton";
+import useHover from "../../../hooks/useHover";
 
-interface IProps {
+interface ExtraTileProps {
     isMinimized: boolean;
     isSelected: boolean;
     displayName: string;
@@ -31,75 +32,62 @@ interface IProps {
     onClick: (ev: ButtonEvent) => void;
 }
 
-interface IState {
+export default function ExtraTile({
-    hover: boolean;
+    isSelected,
-}
+    isMinimized,
+    notificationState,
+    displayName,
+    onClick,
+    avatar,
+}: ExtraTileProps): JSX.Element {
+    const [, { onMouseOver, onMouseLeave }] = useHover(() => false);
 
-export default class ExtraTile extends React.Component<IProps, IState> {
-    public constructor(props: IProps) {
-        super(props);
-
-        this.state = {
-            hover: false,
-        };
-    }
-
-    private onTileMouseEnter = (): void => {
-        this.setState({ hover: true });
-    };
-
-    private onTileMouseLeave = (): void => {
-        this.setState({ hover: false });
-    };
-
-    public render(): React.ReactElement {
     // XXX: We copy classes because it's easier
     const classes = classNames({
         mx_ExtraTile: true,
         mx_RoomTile: true,
-            mx_RoomTile_selected: this.props.isSelected,
+        mx_RoomTile_selected: isSelected,
-            mx_RoomTile_minimized: this.props.isMinimized,
+        mx_RoomTile_minimized: isMinimized,
     });
 
-        let badge;
+    let badge: JSX.Element | null = null;
-        if (this.props.notificationState) {
+    if (notificationState) {
-            badge = <NotificationBadge notification={this.props.notificationState} forceCount={false} />;
+        badge = <NotificationBadge notification={notificationState} forceCount={false} />;
     }
 
-        let name = this.props.displayName;
+    let name = displayName;
     if (typeof name !== "string") name = "";
     name = name.replace(":", ":\u200b"); // add a zero-width space to allow linewrapping after the colon
 
     const nameClasses = classNames({
         mx_RoomTile_title: true,
-            mx_RoomTile_titleHasUnreadEvents: this.props.notificationState?.isUnread,
+        mx_RoomTile_titleHasUnreadEvents: notificationState?.isUnread,
     });
 
-        let nameContainer = (
+    let nameContainer: JSX.Element | null = (
         <div className="mx_RoomTile_titleContainer">
             <div title={name} className={nameClasses} tabIndex={-1} dir="auto">
                 {name}
             </div>
         </div>
     );
-        if (this.props.isMinimized) nameContainer = null;
+    if (isMinimized) nameContainer = null;
 
     let Button = RovingAccessibleButton;
-        if (this.props.isMinimized) {
+    if (isMinimized) {
         Button = RovingAccessibleTooltipButton;
     }
 
     return (
-            <React.Fragment>
         <Button
             className={classes}
-                    onMouseEnter={this.onTileMouseEnter}
+            onMouseEnter={onMouseOver}
-                    onMouseLeave={this.onTileMouseLeave}
+            onMouseLeave={onMouseLeave}
-                    onClick={this.props.onClick}
+            onClick={onClick}
             role="treeitem"
-                    title={this.props.isMinimized ? name : undefined}
+            title={isMinimized ? name : undefined}
         >
-                    <div className="mx_RoomTile_avatarContainer">{this.props.avatar}</div>
+            <div className="mx_RoomTile_avatarContainer">{avatar}</div>
             <div className="mx_RoomTile_details">
                 <div className="mx_RoomTile_primaryDetails">
                     {nameContainer}
@@ -107,7 +95,5 @@ export default class ExtraTile extends React.Component<IProps, IState> {
                 </div>
             </div>
         </Button>
-            </React.Fragment>
     );
 }
-}

src/components/views/rooms/MessageComposer.tsx

@@ -241,7 +241,7 @@ export class MessageComposer extends React.Component<IProps, IState> {
 
     private waitForOwnMember(): void {
         // If we have the member already, do that
-        const me = this.props.room.getMember(MatrixClientPeg.get().getUserId());
+        const me = this.props.room.getMember(MatrixClientPeg.get().getUserId()!);
         if (me) {
             this.setState({ me });
             return;
@@ -250,14 +250,14 @@ export class MessageComposer extends React.Component<IProps, IState> {
         // The members should already be loading, and loadMembersIfNeeded
         // will return the promise for the existing operation
         this.props.room.loadMembersIfNeeded().then(() => {
-            const me = this.props.room.getMember(MatrixClientPeg.get().getUserId());
+            const me = this.props.room.getMember(MatrixClientPeg.get().getUserId()!);
             this.setState({ me });
         });
     }
 
     public componentWillUnmount(): void {
         VoiceRecordingStore.instance.off(UPDATE_EVENT, this.onVoiceStoreUpdate);
-        dis.unregister(this.dispatcherRef);
+        if (this.dispatcherRef) dis.unregister(this.dispatcherRef);
         UIStore.instance.stopTrackingElementDimensions(`MessageComposer${this.instanceId}`);
         UIStore.instance.removeListener(`MessageComposer${this.instanceId}`, this.onResize);
 
@@ -268,12 +268,12 @@ export class MessageComposer extends React.Component<IProps, IState> {
     private onTombstoneClick = (ev: ButtonEvent): void => {
         ev.preventDefault();
 
-        const replacementRoomId = this.context.tombstone.getContent()["replacement_room"];
+        const replacementRoomId = this.context.tombstone?.getContent()["replacement_room"];
         const replacementRoom = MatrixClientPeg.get().getRoom(replacementRoomId);
-        let createEventId = null;
+        let createEventId: string | undefined;
         if (replacementRoom) {
             const createEvent = replacementRoom.currentState.getStateEvents(EventType.RoomCreate, "");
-            if (createEvent && createEvent.getId()) createEventId = createEvent.getId();
+            if (createEvent?.getId()) createEventId = createEvent.getId();
         }
 
         const viaServers = [this.context.tombstone.getSender().split(":").slice(1).join(":")];
@@ -408,7 +408,7 @@ export class MessageComposer extends React.Component<IProps, IState> {
 
     private onRecordingEndingSoon = ({ secondsLeft }: { secondsLeft: number }): void => {
         this.setState({ recordingTimeLeftSeconds: secondsLeft });
-        window.setTimeout(() => this.setState({ recordingTimeLeftSeconds: null }), 3000);
+        window.setTimeout(() => this.setState({ recordingTimeLeftSeconds: undefined }), 3000);
     };
 
     private setStickerPickerOpen = (isStickerPickerOpen: boolean): void => {

src/components/views/rooms/NotificationBadge/StatelessNotificationBadge.tsx

@@ -38,7 +38,7 @@ export function StatelessNotificationBadge({ symbol, count, color, ...props }: P
 
     // Don't show a badge if we don't need to
     if (color === NotificationColor.None || (hideBold && color == NotificationColor.Bold)) {
-        return null;
+        return <></>;
     }
 
     const hasUnreadCount = color >= NotificationColor.Grey && (!!count || !!symbol);
@@ -54,8 +54,8 @@ export function StatelessNotificationBadge({ symbol, count, color, ...props }: P
         mx_NotificationBadge_visible: isEmptyBadge ? true : hasUnreadCount,
         mx_NotificationBadge_highlighted: color >= NotificationColor.Red,
         mx_NotificationBadge_dot: isEmptyBadge,
-        mx_NotificationBadge_2char: symbol?.length > 0 && symbol?.length < 3,
+        mx_NotificationBadge_2char: symbol && symbol.length > 0 && symbol.length < 3,
-        mx_NotificationBadge_3char: symbol?.length > 2,
+        mx_NotificationBadge_3char: symbol && symbol.length > 2,
     });
 
     if (props.onClick) {

src/components/views/rooms/PinnedEventTile.tsx

@@ -62,7 +62,7 @@ export default class PinnedEventTile extends React.Component<IProps> {
         eventId: string,
         relationType: RelationType | string,
         eventType: EventType | string,
-    ): Relations => {
+    ): Relations | undefined => {
         if (eventId === this.props.event.getId()) {
             return this.relations.get(relationType)?.get(eventType);
         }
@@ -71,7 +71,7 @@ export default class PinnedEventTile extends React.Component<IProps> {
     public render(): React.ReactNode {
         const sender = this.props.event.getSender();
 
-        let unpinButton = null;
+        let unpinButton: JSX.Element | undefined;
         if (this.props.onUnpinClicked) {
             unpinButton = (
                 <AccessibleTooltipButton

src/components/views/rooms/ReadReceiptGroup.tsx

@@ -66,7 +66,7 @@ export function determineAvatarPosition(index: number, max: number): IAvatarPosi
     }
 }
 
-export function readReceiptTooltip(members: string[], hasMore: boolean): string | null {
+export function readReceiptTooltip(members: string[], hasMore: boolean): string | undefined {
     if (hasMore) {
         return _t("%(members)s and more", {
             members: members.join(", "),
@@ -78,8 +78,6 @@ export function readReceiptTooltip(members: string[], hasMore: boolean): string
         });
     } else if (members.length) {
         return members[0];
-    } else {
-        return null;
     }
 }
 
@@ -134,7 +132,7 @@ export function ReadReceiptGroup({
             const { hidden, position } = determineAvatarPosition(index, maxAvatars);
 
             const userId = receipt.userId;
-            let readReceiptInfo: IReadReceiptInfo;
+            let readReceiptInfo: IReadReceiptInfo | undefined;
 
             if (readReceiptMap) {
                 readReceiptInfo = readReceiptMap[userId];
@@ -161,7 +159,7 @@ export function ReadReceiptGroup({
         })
         .reverse();
 
-    let remText: JSX.Element;
+    let remText: JSX.Element | undefined;
     const remainder = readReceipts.length - maxAvatars;
     if (remainder > 0) {
         remText = (

src/components/views/rooms/ReadReceiptMarker.tsx

@@ -133,7 +133,7 @@ export default class ReadReceiptMarker extends React.PureComponent<IProps, IStat
 
             target.top = 0;
             target.right = 0;
-            target.parent = null;
+            target.parent = undefined;
             return target;
         }
         // this is the mx_ReadReceiptsGroup
@@ -146,7 +146,7 @@ export default class ReadReceiptMarker extends React.PureComponent<IProps, IStat
 
             target.top = 0;
             target.right = 0;
-            target.parent = null;
+            target.parent = undefined;
             return target;
         }
 
@@ -179,7 +179,7 @@ export default class ReadReceiptMarker extends React.PureComponent<IProps, IStat
             : // treat new RRs as though they were off the top of the screen
               -READ_AVATAR_SIZE;
 
-        const startStyles = [];
+        const startStyles: IReadReceiptMarkerStyle[] = [];
         if (oldInfo?.right) {
             startStyles.push({
                 top: oldPosition - newPosition,
@@ -210,7 +210,7 @@ export default class ReadReceiptMarker extends React.PureComponent<IProps, IStat
         return (
             <NodeAnimator startStyles={this.state.startStyles}>
                 <MemberAvatar
-                    member={this.props.member}
+                    member={this.props.member ?? null}
                     fallbackUserId={this.props.fallbackUserId}
                     aria-hidden="true"
                     aria-live="off"

src/components/views/rooms/ReplyTile.tsx

@@ -168,7 +168,7 @@ export default class ReplyTile extends React.PureComponent<IProps> {
                             ...this.props,
 
                             // overrides
-                            ref: null,
+                            ref: undefined,
                             showUrlPreview: false,
                             overrideBodyTypes: msgtypeOverrides,
                             overrideEventTypes: evOverrides,

src/components/views/rooms/RoomContextDetails.tsx

@@ -37,5 +37,5 @@ export function RoomContextDetails<T extends keyof ReactHTML>({ room, component,
         );
     }
 
-    return null;
+    return <></>;
 }

src/components/views/rooms/RoomInfoLine.tsx

@@ -62,7 +62,7 @@ const RoomInfoLine: FC<IProps> = ({ room }) => {
         roomType = room.isSpaceRoom() ? _t("Private space") : _t("Private room");
     }
 
-    let members: JSX.Element;
+    let members: JSX.Element | undefined;
     if (membership === "invite" && summary) {
         // Don't trust local state and instead use the summary API
         members = (

src/components/views/rooms/RoomList.tsx

@@ -117,7 +117,7 @@ const auxButtonContextMenuPosition = (handle: RefObject<HTMLDivElement>): MenuPr
 
 const DmAuxButton: React.FC<IAuxButtonProps> = ({ tabIndex, dispatcher = defaultDispatcher }) => {
     const [menuDisplayed, handle, openMenu, closeMenu] = useContextMenu<HTMLDivElement>();
-    const activeSpace: Room = useEventEmitterState(SpaceStore.instance, UPDATE_SELECTED_SPACE, () => {
+    const activeSpace = useEventEmitterState(SpaceStore.instance, UPDATE_SELECTED_SPACE, () => {
         return SpaceStore.instance.activeSpaceRoom;
     });
 
@@ -125,7 +125,7 @@ const DmAuxButton: React.FC<IAuxButtonProps> = ({ tabIndex, dispatcher = default
     const showInviteUsers = shouldShowComponent(UIComponent.InviteUsers);
 
     if (activeSpace && (showCreateRooms || showInviteUsers)) {
-        let contextMenu: JSX.Element;
+        let contextMenu: JSX.Element | undefined;
         if (menuDisplayed) {
             const canInvite = shouldShowSpaceInvite(activeSpace);
 
@@ -208,7 +208,7 @@ const DmAuxButton: React.FC<IAuxButtonProps> = ({ tabIndex, dispatcher = default
 
 const UntaggedAuxButton: React.FC<IAuxButtonProps> = ({ tabIndex }) => {
     const [menuDisplayed, handle, openMenu, closeMenu] = useContextMenu<HTMLDivElement>();
-    const activeSpace = useEventEmitterState<Room>(SpaceStore.instance, UPDATE_SELECTED_SPACE, () => {
+    const activeSpace = useEventEmitterState<Room | null>(SpaceStore.instance, UPDATE_SELECTED_SPACE, () => {
         return SpaceStore.instance.activeSpaceRoom;
     });
 
@@ -216,11 +216,11 @@ const UntaggedAuxButton: React.FC<IAuxButtonProps> = ({ tabIndex }) => {
     const videoRoomsEnabled = useFeatureEnabled("feature_video_rooms");
     const elementCallVideoRoomsEnabled = useFeatureEnabled("feature_element_call_video_rooms");
 
-    let contextMenuContent: JSX.Element | null = null;
+    let contextMenuContent: JSX.Element | undefined;
     if (menuDisplayed && activeSpace) {
         const canAddRooms = activeSpace.currentState.maySendStateEvent(
             EventType.SpaceChild,
-            MatrixClientPeg.get().getUserId(),
+            MatrixClientPeg.get().getUserId()!,
         );
 
         contextMenuContent = (
@@ -469,13 +469,13 @@ export default class RoomList extends React.PureComponent<IProps, IState> {
         SpaceStore.instance.off(UPDATE_SUGGESTED_ROOMS, this.updateSuggestedRooms);
         RoomListStore.instance.off(LISTS_UPDATE_EVENT, this.updateLists);
         SettingsStore.unwatchSetting(this.favouriteMessageWatcher);
-        defaultDispatcher.unregister(this.dispatcherRef);
+        if (this.dispatcherRef) defaultDispatcher.unregister(this.dispatcherRef);
         SdkContextClass.instance.roomViewStore.off(UPDATE_EVENT, this.onRoomViewStoreUpdate);
     }
 
     private onRoomViewStoreUpdate = (): void => {
         this.setState({
-            currentRoomId: SdkContextClass.instance.roomViewStore.getRoomId(),
+            currentRoomId: SdkContextClass.instance.roomViewStore.getRoomId() ?? undefined,
         });
     };
 
@@ -629,7 +629,7 @@ export default class RoomList extends React.PureComponent<IProps, IState> {
             Object.values(RoomListStore.instance.orderedLists).every((list) => !list?.length);
 
         return TAG_ORDER.map((orderedTagId) => {
-            let extraTiles = null;
+            let extraTiles: ReactComponentElement<typeof ExtraTile>[] | undefined;
             if (orderedTagId === DefaultTagID.Suggested) {
                 extraTiles = this.renderSuggestedRooms();
             } else if (this.state.feature_favourite_messages && orderedTagId === DefaultTagID.SavedItems) {

src/components/views/rooms/RoomListHeader.tsx

@@ -137,12 +137,10 @@ const RoomListHeader: React.FC<IProps> = ({ onVisibilityChange }) => {
         }
     }, [closeMainMenu, canShowMainMenu, mainMenuDisplayed]);
 
-    const spaceName = useTypedEventEmitterState(activeSpace, RoomEvent.Name, () => activeSpace?.name);
+    const spaceName = useTypedEventEmitterState(activeSpace ?? undefined, RoomEvent.Name, () => activeSpace?.name);
 
     useEffect(() => {
-        if (onVisibilityChange) {
+        onVisibilityChange?.();
-            onVisibilityChange();
-        }
     }, [onVisibilityChange]);
 
     const canExploreRooms = shouldShowComponent(UIComponent.ExploreRooms);
@@ -151,7 +149,7 @@ const RoomListHeader: React.FC<IProps> = ({ onVisibilityChange }) => {
 
     const hasPermissionToAddSpaceChild = activeSpace?.currentState?.maySendStateEvent(
         EventType.SpaceChild,
-        cli.getUserId(),
+        cli.getUserId()!,
     );
     const canAddSubRooms = hasPermissionToAddSpaceChild && canCreateRooms;
     const canAddSubSpaces = hasPermissionToAddSpaceChild && canCreateSpaces;
@@ -161,7 +159,7 @@ const RoomListHeader: React.FC<IProps> = ({ onVisibilityChange }) => {
     // communities and spaces, but is at risk of no options on the Home tab.
     const canShowPlusMenu = canCreateRooms || canExploreRooms || canCreateSpaces || activeSpace;
 
-    let contextMenu: JSX.Element;
+    let contextMenu: JSX.Element | undefined;
     if (mainMenuDisplayed && mainMenuHandle.current) {
         let ContextMenuComponent;
         if (activeSpace) {
@@ -179,7 +177,7 @@ const RoomListHeader: React.FC<IProps> = ({ onVisibilityChange }) => {
             />
         );
     } else if (plusMenuDisplayed && activeSpace) {
-        let inviteOption: JSX.Element;
+        let inviteOption: JSX.Element | undefined;
         if (shouldShowSpaceInvite(activeSpace)) {
             inviteOption = (
                 <IconizedContextMenuOption
@@ -195,8 +193,8 @@ const RoomListHeader: React.FC<IProps> = ({ onVisibilityChange }) => {
             );
         }
 
-        let newRoomOptions: JSX.Element;
+        let newRoomOptions: JSX.Element | undefined;
-        if (activeSpace?.currentState.maySendStateEvent(EventType.RoomAvatar, cli.getUserId())) {
+        if (activeSpace?.currentState.maySendStateEvent(EventType.RoomAvatar, cli.getUserId()!)) {
             newRoomOptions = (
                 <>
                     <IconizedContextMenuOption
@@ -265,7 +263,9 @@ const RoomListHeader: React.FC<IProps> = ({ onVisibilityChange }) => {
                             closePlusMenu();
                         }}
                         disabled={!canAddSubRooms}
-                        tooltip={!canAddSubRooms && _t("You do not have permissions to add rooms to this space")}
+                        tooltip={
+                            !canAddSubRooms ? _t("You do not have permissions to add rooms to this space") : undefined
+                        }
                     />
                     {canCreateSpaces && (
                         <IconizedContextMenuOption
@@ -278,7 +278,11 @@ const RoomListHeader: React.FC<IProps> = ({ onVisibilityChange }) => {
                                 closePlusMenu();
                             }}
                             disabled={!canAddSubSpaces}
-                            tooltip={!canAddSubSpaces && _t("You do not have permissions to add spaces to this space")}
+                            tooltip={
+                                !canAddSubSpaces
+                                    ? _t("You do not have permissions to add spaces to this space")
+                                    : undefined
+                            }
                         >
                             <BetaPill />
                         </IconizedContextMenuOption>
@@ -287,8 +291,8 @@ const RoomListHeader: React.FC<IProps> = ({ onVisibilityChange }) => {
             </IconizedContextMenu>
         );
     } else if (plusMenuDisplayed) {
-        let newRoomOpts: JSX.Element;
+        let newRoomOpts: JSX.Element | undefined;
-        let joinRoomOpt: JSX.Element;
+        let joinRoomOpt: JSX.Element | undefined;
 
         if (canCreateRooms) {
             newRoomOpts = (
@@ -366,7 +370,7 @@ const RoomListHeader: React.FC<IProps> = ({ onVisibilityChange }) => {
     }
 
     let title: string;
-    if (activeSpace) {
+    if (activeSpace && spaceName) {
         title = spaceName;
     } else {
         title = getMetaSpaceName(spaceKey as MetaSpace, allRoomsInHome);

src/components/views/rooms/RoomPreviewBar.tsx

@@ -14,7 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import React from "react";
+import React, { ReactNode } from "react";
 import { Room } from "matrix-js-sdk/src/models/room";
 import { MatrixError } from "matrix-js-sdk/src/http-api";
 import { EventType, RoomType } from "matrix-js-sdk/src/@types/event";
@@ -76,6 +76,12 @@ interface IProps {
 
     canPreview?: boolean;
     previewLoading?: boolean;
+
+    // The id of the room to be previewed, if it is known.
+    // (It may be unknown if we are waiting for an alias to be resolved.)
+    roomId?: string;
+
+    // A `Room` object for the room to be previewed, if we have one.
     room?: Room;
 
     loading?: boolean;
@@ -215,25 +221,27 @@ export default class RoomPreviewBar extends React.Component<IProps, IState> {
         return { memberName, reason };
     }
 
-    private joinRule(): JoinRule {
+    private joinRule(): JoinRule | null {
-        return this.props.room?.currentState
+        return (
+            this.props.room?.currentState
                 .getStateEvents(EventType.RoomJoinRules, "")
-            ?.getContent<IJoinRuleEventContent>().join_rule;
+                ?.getContent<IJoinRuleEventContent>().join_rule ?? null
+        );
     }
 
-    private getMyMember(): RoomMember {
+    private getMyMember(): RoomMember | null {
-        return this.props.room?.getMember(MatrixClientPeg.get().getUserId());
+        return this.props.room?.getMember(MatrixClientPeg.get().getUserId()!) ?? null;
     }
 
-    private getInviteMember(): RoomMember {
+    private getInviteMember(): RoomMember | null {
         const { room } = this.props;
         if (!room) {
-            return;
+            return null;
         }
-        const myUserId = MatrixClientPeg.get().getUserId();
+        const myUserId = MatrixClientPeg.get().getUserId()!;
         const inviteEvent = room.currentState.getMember(myUserId);
         if (!inviteEvent) {
-            return;
+            return null;
         }
         const inviterUserId = inviteEvent.events.member.getSender();
         return room.currentState.getMember(inviterUserId);
@@ -276,15 +284,15 @@ export default class RoomPreviewBar extends React.Component<IProps, IState> {
         const isSpace = this.props.room?.isSpaceRoom() ?? this.props.oobData?.roomType === RoomType.Space;
 
         let showSpinner = false;
-        let title;
+        let title: string | undefined;
-        let subTitle;
+        let subTitle: string | ReactNode[] | undefined;
-        let reasonElement;
+        let reasonElement: JSX.Element | undefined;
-        let primaryActionHandler;
+        let primaryActionHandler: (() => void) | undefined;
-        let primaryActionLabel;
+        let primaryActionLabel: string | undefined;
-        let secondaryActionHandler;
+        let secondaryActionHandler: (() => void) | undefined;
-        let secondaryActionLabel;
+        let secondaryActionLabel: string | undefined;
-        let footer;
+        let footer: JSX.Element | undefined;
-        const extraComponents = [];
+        const extraComponents: JSX.Element[] = [];
 
         const messageCase = this.getMessageCase();
         switch (messageCase) {
@@ -310,18 +318,14 @@ export default class RoomPreviewBar extends React.Component<IProps, IState> {
             }
             case MessageCase.NotLoggedIn: {
                 const opts: RoomPreviewOpts = { canJoin: false };
-                if (this.props.room?.roomId) {
+                if (this.props.roomId) {
-                    ModuleRunner.instance.invoke(
+                    ModuleRunner.instance.invoke(RoomViewLifecycle.PreviewRoomNotLoggedIn, opts, this.props.roomId);
-                        RoomViewLifecycle.PreviewRoomNotLoggedIn,
-                        opts,
-                        this.props.room.roomId,
-                    );
                 }
                 if (opts.canJoin) {
                     title = _t("Join the room to participate");
                     primaryActionLabel = _t("Join");
                     primaryActionHandler = () => {
-                        ModuleRunner.instance.invoke(RoomViewLifecycle.JoinFromRoomPreview, this.props.room.roomId);
+                        ModuleRunner.instance.invoke(RoomViewLifecycle.JoinFromRoomPreview, this.props.roomId);
                     };
                 } else {
                     title = _t("Join the conversation with an account");
@@ -349,7 +353,7 @@ export default class RoomPreviewBar extends React.Component<IProps, IState> {
                 } else {
                     title = _t("You were removed by %(memberName)s", { memberName });
                 }
-                subTitle = reason ? _t("Reason: %(reason)s", { reason }) : null;
+                subTitle = reason ? _t("Reason: %(reason)s", { reason }) : undefined;
 
                 if (isSpace) {
                     primaryActionLabel = _t("Forget this space");
@@ -374,7 +378,7 @@ export default class RoomPreviewBar extends React.Component<IProps, IState> {
                 } else {
                     title = _t("You were banned by %(memberName)s", { memberName });
                 }
-                subTitle = reason ? _t("Reason: %(reason)s", { reason }) : null;
+                subTitle = reason ? _t("Reason: %(reason)s", { reason }) : undefined;
                 if (isSpace) {
                     primaryActionLabel = _t("Forget this space");
                 } else {
@@ -497,7 +501,7 @@ export default class RoomPreviewBar extends React.Component<IProps, IState> {
                     primaryActionLabel = _t("Accept");
                 }
 
-                const myUserId = MatrixClientPeg.get().getUserId();
+                const myUserId = MatrixClientPeg.get().getUserId()!;
                 const member = this.props.room?.currentState.getMember(myUserId);
                 const memberEventContent = member?.events.member?.getContent();
 

src/components/views/rooms/RoomSublist.tsx

@@ -22,7 +22,7 @@ import { Dispatcher } from "flux";
 import { Enable, Resizable } from "re-resizable";
 import { Direction } from "re-resizable/lib/resizer";
 import * as React from "react";
-import { ComponentType, createRef, ReactComponentElement } from "react";
+import { ComponentType, createRef, ReactComponentElement, ReactNode } from "react";
 
 import { polyfillTouchEvent } from "../../../@types/polyfill";
 import { KeyBindingAction } from "../../../accessibility/KeyboardShortcuts";
@@ -82,7 +82,7 @@ interface IProps {
     alwaysVisible?: boolean;
     forceExpanded?: boolean;
     resizeNotifier: ResizeNotifier;
-    extraTiles?: ReactComponentElement<typeof ExtraTile>[];
+    extraTiles?: ReactComponentElement<typeof ExtraTile>[] | null;
     onListCollapse?: (isExpanded: boolean) => void;
 }
 
@@ -95,7 +95,7 @@ interface ResizeDelta {
 type PartialDOMRect = Pick<DOMRect, "left" | "top" | "height">;
 
 interface IState {
-    contextMenuPosition: PartialDOMRect;
+    contextMenuPosition?: PartialDOMRect;
     isResizing: boolean;
     isExpanded: boolean; // used for the for expand of the sublist when the room list is being filtered
     height: number;
@@ -123,7 +123,6 @@ export default class RoomSublist extends React.Component<IProps, IState> {
         this.heightAtStart = 0;
         this.notificationState = RoomNotificationStateStore.instance.getListState(this.props.tagId);
         this.state = {
-            contextMenuPosition: null,
             isResizing: false,
             isExpanded: !this.layout.isCollapsed,
             height: 0, // to be fixed in a moment, we need `rooms` to calculate this.
@@ -160,17 +159,14 @@ export default class RoomSublist extends React.Component<IProps, IState> {
     }
 
     private get extraTiles(): ReactComponentElement<typeof ExtraTile>[] | null {
-        if (this.props.extraTiles) {
+        return this.props.extraTiles ?? null;
-            return this.props.extraTiles;
-        }
-        return null;
     }
 
     private get numTiles(): number {
         return RoomSublist.calcNumTiles(this.state.rooms, this.extraTiles);
     }
 
-    private static calcNumTiles(rooms: Room[], extraTiles: any[]): number {
+    private static calcNumTiles(rooms: Room[], extraTiles?: any[] | null): number {
         return (rooms || []).length + (extraTiles || []).length;
     }
 
@@ -390,7 +386,7 @@ export default class RoomSublist extends React.Component<IProps, IState> {
     };
 
     private onCloseMenu = (): void => {
-        this.setState({ contextMenuPosition: null });
+        this.setState({ contextMenuPosition: undefined });
     };
 
     private onUnreadFirstChanged = (): void => {
@@ -506,7 +502,7 @@ export default class RoomSublist extends React.Component<IProps, IState> {
             // On ArrowLeft go to the sublist header
             case KeyBindingAction.ArrowLeft:
                 ev.stopPropagation();
-                this.headerButton.current.focus();
+                this.headerButton.current?.focus();
                 break;
             // Consume ArrowRight so it doesn't cause focus to get sent to composer
             case KeyBindingAction.ArrowRight:
@@ -557,10 +553,10 @@ export default class RoomSublist extends React.Component<IProps, IState> {
         return tiles;
     }
 
-    private renderMenu(): React.ReactElement {
+    private renderMenu(): ReactNode {
         if (this.props.tagId === DefaultTagID.Suggested || this.props.tagId === DefaultTagID.SavedItems) return null; // not sortable
 
-        let contextMenu = null;
+        let contextMenu: JSX.Element | undefined;
         if (this.state.contextMenuPosition) {
             let isAlphabetical = RoomListStore.instance.getTagSorting(this.props.tagId) === SortAlgorithm.Alphabetic;
             let isUnreadFirst = RoomListStore.instance.getListOrder(this.props.tagId) === ListAlgorithm.Importance;
@@ -571,7 +567,7 @@ export default class RoomSublist extends React.Component<IProps, IState> {
             }
 
             // Invites don't get some nonsense options, so only add them if we have to.
-            let otherSections = null;
+            let otherSections: JSX.Element | undefined;
             if (this.props.tagId !== DefaultTagID.Invite) {
                 otherSections = (
                     <React.Fragment>
@@ -665,7 +661,7 @@ export default class RoomSublist extends React.Component<IProps, IState> {
                         />
                     );
 
-                    let addRoomButton = null;
+                    let addRoomButton: JSX.Element | undefined;
                     if (this.props.AuxButtonComponent) {
                         const AuxButtonComponent = this.props.AuxButtonComponent;
                         addRoomButton = <AuxButtonComponent tabIndex={tabIndex} />;
@@ -747,7 +743,7 @@ export default class RoomSublist extends React.Component<IProps, IState> {
             mx_RoomSublist_hidden: hidden,
         });
 
-        let content = null;
+        let content: JSX.Element | undefined;
         if (this.state.roomsLoading) {
             content = <div className="mx_RoomSublist_skeletonUI" />;
         } else if (visibleTiles.length > 0 && this.props.forceExpanded) {
@@ -773,7 +769,7 @@ export default class RoomSublist extends React.Component<IProps, IState> {
             // If we're hiding rooms, show a 'show more' button to the user. This button
             // floats above the resize handle, if we have one present. If the user has all
             // tiles visible, it becomes 'show less'.
-            let showNButton = null;
+            let showNButton: JSX.Element | undefined;
             const hasMoreSlidingSync =
                 this.slidingSyncMode && RoomListStore.instance.getCount(this.props.tagId) > this.state.rooms.length;
 
@@ -786,7 +782,7 @@ export default class RoomSublist extends React.Component<IProps, IState> {
                     numMissing = RoomListStore.instance.getCount(this.props.tagId) - amountFullyShown;
                 }
                 const label = _t("Show %(count)s more", { count: numMissing });
-                let showMoreText = <span className="mx_RoomSublist_showNButtonText">{label}</span>;
+                let showMoreText: ReactNode = <span className="mx_RoomSublist_showNButtonText">{label}</span>;
                 if (this.props.isMinimized) showMoreText = null;
                 showNButton = (
                     <RovingAccessibleButton
@@ -804,7 +800,7 @@ export default class RoomSublist extends React.Component<IProps, IState> {
             } else if (this.numTiles > this.layout.defaultVisibleTiles) {
                 // we have all tiles visible - add a button to show less
                 const label = _t("Show less");
-                let showLessText = <span className="mx_RoomSublist_showNButtonText">{label}</span>;
+                let showLessText: ReactNode = <span className="mx_RoomSublist_showNButtonText">{label}</span>;
                 if (this.props.isMinimized) showLessText = null;
                 showNButton = (
                     <RovingAccessibleButton

src/components/views/rooms/SearchBar.tsx

@@ -72,13 +72,13 @@ export default class SearchBar extends React.Component<IProps, IState> {
     };
 
     private searchIfQuery(): void {
-        if (this.searchTerm.current.value) {
+        if (this.searchTerm.current?.value) {
             this.onSearch();
         }
     }
 
     private onSearch = (): void => {
-        if (!this.searchTerm.current.value.trim()) return;
+        if (!this.searchTerm.current?.value.trim()) return;
         this.props.onSearch(this.searchTerm.current.value, this.state.scope);
     };
 

src/components/views/rooms/SendMessageComposer.tsx

@@ -368,7 +368,12 @@ export class SendMessageComposer extends React.Component<ISendMessageComposerPro
                     this.props.relation?.rel_type === THREAD_RELATION_TYPE.name ? this.props.relation?.event_id : null;
 
                 let commandSuccessful: boolean;
-                [content, commandSuccessful] = await runSlashCommand(cmd, args, this.props.room.roomId, threadId);
+                [content, commandSuccessful] = await runSlashCommand(
+                    cmd,
+                    args,
+                    this.props.room.roomId,
+                    threadId ?? null,
+                );
                 if (!commandSuccessful) {
                     return; // errored
                 }
@@ -425,7 +430,7 @@ export class SendMessageComposer extends React.Component<ISendMessageComposerPro
 
             const prom = doMaybeLocalRoomAction(
                 roomId,
-                (actualRoomId: string) => this.props.mxClient.sendMessage(actualRoomId, threadId, content),
+                (actualRoomId: string) => this.props.mxClient.sendMessage(actualRoomId, threadId ?? null, content!),
                 this.props.mxClient,
             );
             if (replyToEvent) {
@@ -439,7 +444,7 @@ export class SendMessageComposer extends React.Component<ISendMessageComposerPro
             }
             dis.dispatch({ action: "message_sent" });
             CHAT_EFFECTS.forEach((effect) => {
-                if (containsEmoji(content, effect.emojis)) {
+                if (containsEmoji(content!, effect.emojis)) {
                     // For initial threads launch, chat effects are disabled
                     // see #19731
                     const isNotThread = this.props.relation?.rel_type !== THREAD_RELATION_TYPE.name;

src/components/views/rooms/Stickerpicker.tsx

@@ -52,9 +52,9 @@ interface IProps {
 }
 
 interface IState {
-    imError: string;
+    imError: string | null;
-    stickerpickerWidget: IWidgetEvent;
+    stickerpickerWidget: IWidgetEvent | null;
-    widgetId: string;
+    widgetId: string | null;
 }
 
 export default class Stickerpicker extends React.PureComponent<IProps, IState> {
@@ -71,7 +71,7 @@ export default class Stickerpicker extends React.PureComponent<IProps, IState> {
     private popoverWidth = 300;
     private popoverHeight = 300;
     // This is loaded by _acquireScalarClient on an as-needed basis.
-    private scalarClient: ScalarAuthClient = null;
+    private scalarClient: ScalarAuthClient | null = null;
 
     public constructor(props: IProps) {
         super(props);
@@ -82,13 +82,13 @@ export default class Stickerpicker extends React.PureComponent<IProps, IState> {
         };
     }
 
-    private acquireScalarClient(): Promise<void | ScalarAuthClient> {
+    private async acquireScalarClient(): Promise<void | undefined | null | ScalarAuthClient> {
         if (this.scalarClient) return Promise.resolve(this.scalarClient);
         // TODO: Pick the right manager for the widget
         if (IntegrationManagers.sharedInstance().hasManager()) {
-            this.scalarClient = IntegrationManagers.sharedInstance().getPrimaryManager().getScalarClient();
+            this.scalarClient = IntegrationManagers.sharedInstance().getPrimaryManager()?.getScalarClient() ?? null;
             return this.scalarClient
-                .connect()
+                ?.connect()
                 .then(() => {
                     this.forceUpdate();
                     return this.scalarClient;
@@ -170,21 +170,14 @@ export default class Stickerpicker extends React.PureComponent<IProps, IState> {
     private updateWidget = (): void => {
         const stickerpickerWidget = WidgetUtils.getStickerpickerWidgets()[0];
         if (!stickerpickerWidget) {
-            Stickerpicker.currentWidget = null;
+            Stickerpicker.currentWidget = undefined;
             this.setState({ stickerpickerWidget: null, widgetId: null });
             return;
         }
 
         const currentWidget = Stickerpicker.currentWidget;
-        let currentUrl = null;
+        const currentUrl = currentWidget?.content?.url ?? null;
-        if (currentWidget && currentWidget.content && currentWidget.content.url) {
+        const newUrl = stickerpickerWidget?.content?.url ?? null;
-            currentUrl = currentWidget.content.url;
-        }
-
-        let newUrl = null;
-        if (stickerpickerWidget && stickerpickerWidget.content && stickerpickerWidget.content.url) {
-            newUrl = stickerpickerWidget.content.url;
-        }
 
         if (newUrl !== currentUrl) {
             // Destroy the existing frame so a new one can be created
@@ -238,7 +231,7 @@ export default class Stickerpicker extends React.PureComponent<IProps, IState> {
     private sendVisibilityToWidget(visible: boolean): void {
         if (!this.state.stickerpickerWidget) return;
         const messaging = WidgetMessagingStore.instance.getMessagingForUid(
-            WidgetUtils.calcWidgetUid(this.state.stickerpickerWidget.id, null),
+            WidgetUtils.calcWidgetUid(this.state.stickerpickerWidget.id),
         );
         if (messaging && visible !== this.prevSentVisibility) {
             messaging.updateVisibility(visible).catch((err) => {
@@ -300,8 +293,8 @@ export default class Stickerpicker extends React.PureComponent<IProps, IState> {
                                 room={this.props.room}
                                 threadId={this.props.threadId}
                                 fullWidth={true}
-                                userId={MatrixClientPeg.get().credentials.userId}
+                                userId={MatrixClientPeg.get().credentials.userId!}
-                                creatorUserId={stickerpickerWidget.sender || MatrixClientPeg.get().credentials.userId}
+                                creatorUserId={stickerpickerWidget.sender || MatrixClientPeg.get().credentials.userId!}
                                 waitForIframeLoad={true}
                                 showMenubar={true}
                                 onEditClick={this.launchManageIntegrations}
@@ -347,8 +340,8 @@ export default class Stickerpicker extends React.PureComponent<IProps, IState> {
     private launchManageIntegrations = (): void => {
         // noinspection JSIgnoredPromiseFromCall
         IntegrationManagers.sharedInstance()
-            .getPrimaryManager()
+            ?.getPrimaryManager()
-            .open(this.props.room, `type_${WidgetType.STICKERPICKER.preferred}`, this.state.widgetId);
+            ?.open(this.props.room, `type_${WidgetType.STICKERPICKER.preferred}`, this.state.widgetId ?? undefined);
     };
 
     public render(): React.ReactNode {

src/components/views/rooms/ThirdPartyMemberInfo.tsx

@@ -45,19 +45,19 @@ interface IState {
 }
 
 export default class ThirdPartyMemberInfo extends React.Component<IProps, IState> {
-    private room: Room;
+    private readonly room: Room | null;
 
     public constructor(props: IProps) {
         super(props);
 
         this.room = MatrixClientPeg.get().getRoom(this.props.event.getRoomId());
-        const me = this.room.getMember(MatrixClientPeg.get().getUserId());
+        const me = this.room?.getMember(MatrixClientPeg.get().getUserId()!);
-        const powerLevels = this.room.currentState.getStateEvents("m.room.power_levels", "");
+        const powerLevels = this.room?.currentState.getStateEvents("m.room.power_levels", "");
 
         let kickLevel = powerLevels ? powerLevels.getContent().kick : 50;
         if (typeof kickLevel !== "number") kickLevel = 50;
 
-        const sender = this.room.getMember(this.props.event.getSender());
+        const sender = this.room?.getMember(this.props.event.getSender());
 
         this.state = {
             stateKey: this.props.event.getStateKey(),
@@ -121,7 +121,7 @@ export default class ThirdPartyMemberInfo extends React.Component<IProps, IState
     };
 
     public render(): React.ReactNode {
-        let adminTools = null;
+        let adminTools: JSX.Element | undefined;
         if (this.state.canKick && this.state.invited) {
             adminTools = (
                 <div className="mx_MemberInfo_container">
@@ -135,8 +135,8 @@ export default class ThirdPartyMemberInfo extends React.Component<IProps, IState
             );
         }
 
-        let scopeHeader;
+        let scopeHeader: JSX.Element | undefined;
-        if (this.room.isSpaceRoom()) {
+        if (this.room?.isSpaceRoom()) {
             scopeHeader = (
                 <div className="mx_RightPanel_scopeHeader">
                     <RoomAvatar room={this.room} height={32} width={32} />

src/components/views/rooms/ThreadSummary.tsx

@@ -77,18 +77,18 @@ interface IPreviewProps {
 export const ThreadMessagePreview: React.FC<IPreviewProps> = ({ thread, showDisplayname = false }) => {
     const cli = useContext(MatrixClientContext);
 
-    const lastReply = useTypedEventEmitterState(thread, ThreadEvent.Update, () => thread.replyToEvent);
+    const lastReply = useTypedEventEmitterState(thread, ThreadEvent.Update, () => thread.replyToEvent) ?? undefined;
     // track the content as a means to regenerate the thread message preview upon edits & decryption
-    const [content, setContent] = useState<IContent>(lastReply?.getContent());
+    const [content, setContent] = useState<IContent | undefined>(lastReply?.getContent());
     useTypedEventEmitter(lastReply, MatrixEventEvent.Replaced, () => {
-        setContent(lastReply.getContent());
+        setContent(lastReply!.getContent());
     });
     const awaitDecryption = lastReply?.shouldAttemptDecryption() || lastReply?.isBeingDecrypted();
-    useTypedEventEmitter(awaitDecryption ? lastReply : null, MatrixEventEvent.Decrypted, () => {
+    useTypedEventEmitter(awaitDecryption ? lastReply : undefined, MatrixEventEvent.Decrypted, () => {
-        setContent(lastReply.getContent());
+        setContent(lastReply!.getContent());
     });
 
-    const preview = useAsyncMemo(async (): Promise<string> => {
+    const preview = useAsyncMemo(async (): Promise<string | undefined> => {
         if (!lastReply) return;
         await cli.decryptEventIfNeeded(lastReply);
         return MessagePreviewStore.instance.generatePreviewForEvent(lastReply);

src/components/views/rooms/TopUnreadMessagesBar.tsx

@@ -20,8 +20,8 @@ import { _t } from "../../../languageHandler";
 import AccessibleButton from "../elements/AccessibleButton";
 
 interface IProps {
-    onScrollUpClick?: (e: React.MouseEvent) => void;
+    onScrollUpClick: (e: React.MouseEvent) => void;
-    onCloseClick?: (e: React.MouseEvent) => void;
+    onCloseClick: (e: React.MouseEvent) => void;
 }
 
 export default class TopUnreadMessagesBar extends React.PureComponent<IProps> {

src/components/views/rooms/VoiceRecordComposerTile.tsx

@@ -48,7 +48,7 @@ import { createVoiceMessageContent } from "../../../utils/createVoiceMessageCont
 
 interface IProps {
     room: Room;
-    permalinkCreator?: RoomPermalinkCreator;
+    permalinkCreator: RoomPermalinkCreator;
     relation?: IEventRelation;
     replyToEvent?: MatrixEvent;
 }
@@ -70,9 +70,7 @@ export default class VoiceRecordComposerTile extends React.PureComponent<IProps,
     public constructor(props: IProps) {
         super(props);
 
-        this.state = {
+        this.state = {};
-            recorder: null, // no recording started by default
-        };
 
         this.voiceRecordingId = VoiceRecordingStore.getVoiceRecordingId(this.props.room, this.props.relation);
     }
@@ -163,7 +161,7 @@ export default class VoiceRecordComposerTile extends React.PureComponent<IProps,
         await VoiceRecordingStore.instance.disposeRecording(this.voiceRecordingId);
 
         // Reset back to no recording, which means no phase (ie: restart component entirely)
-        this.setState({ recorder: null, recordingPhase: null, didUploadFail: false });
+        this.setState({ recorder: undefined, recordingPhase: undefined, didUploadFail: false });
     }
 
     private onCancel = async (): Promise<void> => {
@@ -220,7 +218,7 @@ export default class VoiceRecordComposerTile extends React.PureComponent<IProps,
 
         try {
             // stop any noises which might be happening
-            PlaybackManager.instance.pauseAllExcept(null);
+            PlaybackManager.instance.pauseAllExcept();
             const recorder = VoiceRecordingStore.instance.startRecording(this.voiceRecordingId);
             await recorder.start();