Make more of the codebase conform to strict types (#10857)

src/AddThreepid.ts

@@ -56,7 +56,7 @@ export default class AddThreepid {
     private sessionId: string;
     private submitUrl?: string;
     private clientSecret: string;
-    private bind: boolean;
+    private bind = false;
 
     public constructor() {
         this.clientSecret = MatrixClientPeg.get().generateClientSecret();

src/ContentMessages.ts

@@ -580,13 +580,13 @@ export default class ContentMessages {
         } catch (error) {
             // 413: File was too big or upset the server in some way:
             // clear the media size limit so we fetch it again next time we try to upload
-            if (error?.httpStatus === 413) {
+            if (error instanceof HTTPError && error.httpStatus === 413) {
                 this.mediaConfig = null;
             }
 
             if (!upload.cancelled) {
                 let desc = _t("The file '%(fileName)s' failed to upload.", { fileName: upload.fileName });
-                if (error.httpStatus === 413) {
+                if (error instanceof HTTPError && error.httpStatus === 413) {
                     desc = _t("The file '%(fileName)s' exceeds this homeserver's size limit for uploads", {
                         fileName: upload.fileName,
                     });

src/IdentityAuthClient.tsx

@@ -16,7 +16,7 @@ limitations under the License.
 
 import React from "react";
 import { SERVICE_TYPES } from "matrix-js-sdk/src/service-types";
-import { createClient, MatrixClient } from "matrix-js-sdk/src/matrix";
+import { createClient, MatrixClient, MatrixError } from "matrix-js-sdk/src/matrix";
 import { logger } from "matrix-js-sdk/src/logger";
 
 import { MatrixClientPeg } from "./MatrixClientPeg";
@@ -123,7 +123,7 @@ export default class IdentityAuthClient {
         try {
             await this.matrixClient.getIdentityAccount(token);
         } catch (e) {
-            if (e.errcode === "M_TERMS_NOT_SIGNED") {
+            if (e instanceof MatrixError && e.errcode === "M_TERMS_NOT_SIGNED") {
                 logger.log("Identity server requires new terms to be agreed to");
                 await startTermsFlow([new Service(SERVICE_TYPES.IS, identityServerUrl, token)]);
                 return;

src/Notifier.ts

@@ -132,7 +132,7 @@ class NotifierClass {
         let msg = this.notificationMessageForEvent(ev);
         if (!msg) return;
 
-        let title;
+        let title: string | undefined;
         if (!ev.sender || room.name === ev.sender.name) {
             title = room.name;
             // notificationMessageForEvent includes sender, but we already have the sender here
@@ -153,6 +153,8 @@ class NotifierClass {
             }
         }
 
+        if (!title) return;
+
         if (!this.isBodyEnabled()) {
             msg = "";
         }

src/SlidingSyncManager.ts

@@ -118,7 +118,7 @@ export class SlidingSyncManager {
     private static readonly internalInstance = new SlidingSyncManager();
 
     public slidingSync: SlidingSync;
-    private client: MatrixClient;
+    private client?: MatrixClient;
 
     private configureDefer: IDeferred<void>;
 
@@ -242,8 +242,8 @@ export class SlidingSyncManager {
         } else {
             subscriptions.delete(roomId);
         }
-        const room = this.client.getRoom(roomId);
+        const room = this.client?.getRoom(roomId);
-        let shouldLazyLoad = !this.client.isRoomEncrypted(roomId);
+        let shouldLazyLoad = !this.client?.isRoomEncrypted(roomId);
         if (!room) {
             // default to safety: request all state if we can't work it out. This can happen if you
             // refresh the app whilst viewing a room: we call setRoomVisible before we know anything

src/accessibility/KeyboardShortcutUtils.ts

@@ -95,8 +95,8 @@ const getUIOnlyShortcuts = (): IKeyboardShortcuts => {
 export const getKeyboardShortcuts = (): IKeyboardShortcuts => {
     const overrideBrowserShortcuts = PlatformPeg.get()?.overrideBrowserShortcuts();
 
-    return Object.keys(KEYBOARD_SHORTCUTS)
+    return (Object.keys(KEYBOARD_SHORTCUTS) as KeyBindingAction[])
-        .filter((k: KeyBindingAction) => {
+        .filter((k) => {
             if (KEYBOARD_SHORTCUTS[k]?.controller?.settingDisabled) return false;
             if (MAC_ONLY_SHORTCUTS.includes(k) && !IS_MAC) return false;
             if (DESKTOP_SHORTCUTS.includes(k) && !overrideBrowserShortcuts) return false;

src/async-components/views/dialogs/security/CreateSecretStorageDialog.tsx

@@ -20,7 +20,7 @@ import FileSaver from "file-saver";
 import { logger } from "matrix-js-sdk/src/logger";
 import { IKeyBackupInfo } from "matrix-js-sdk/src/crypto/keybackup";
 import { TrustInfo } from "matrix-js-sdk/src/crypto/backup";
-import { CrossSigningKeys, UIAFlow } from "matrix-js-sdk/src/matrix";
+import { CrossSigningKeys, MatrixError, UIAFlow } from "matrix-js-sdk/src/matrix";
 import { IRecoveryKey } from "matrix-js-sdk/src/crypto/api";
 import { CryptoEvent } from "matrix-js-sdk/src/crypto";
 import classNames from "classnames";
@@ -103,7 +103,7 @@ export default class CreateSecretStorageDialog extends React.PureComponent<IProp
         forceReset: false,
     };
     private recoveryKey: IRecoveryKey;
-    private backupKey: Uint8Array;
+    private backupKey?: Uint8Array;
     private recoveryKeyNode = createRef<HTMLElement>();
     private passphraseField = createRef<Field>();
 
@@ -208,7 +208,7 @@ export default class CreateSecretStorageDialog extends React.PureComponent<IProp
             // no keys which would be a no-op.
             logger.log("uploadDeviceSigningKeys unexpectedly succeeded without UI auth!");
         } catch (error) {
-            if (!error.data || !error.data.flows) {
+            if (!(error instanceof MatrixError) || !error.data || !error.data.flows) {
                 logger.log("uploadDeviceSigningKeys advertised no flows!");
                 return;
             }
@@ -372,7 +372,12 @@ export default class CreateSecretStorageDialog extends React.PureComponent<IProp
                 phase: Phase.Stored,
             });
         } catch (e) {
-            if (this.state.canUploadKeysWithPasswordOnly && e.httpStatus === 401 && e.data.flows) {
+            if (
+                this.state.canUploadKeysWithPasswordOnly &&
+                e instanceof MatrixError &&
+                e.httpStatus === 401 &&
+                e.data.flows
+            ) {
                 this.setState({
                     accountPassword: "",
                     accountPasswordCorrect: false,

src/boundThreepids.ts

@@ -16,6 +16,7 @@ limitations under the License.
 
 import { IThreepid, ThreepidMedium } from "matrix-js-sdk/src/@types/threepids";
 import { MatrixClient } from "matrix-js-sdk/src/client";
+import { MatrixError } from "matrix-js-sdk/src/http-api";
 
 import IdentityAuthClient from "./IdentityAuthClient";
 
@@ -57,7 +58,7 @@ export async function getThreepidsWithBindStatus(
             }
         } catch (e) {
             // Ignore terms errors here and assume other flows handle this
-            if (e.errcode !== "M_TERMS_NOT_SIGNED") {
+            if (!(e instanceof MatrixError) || e.errcode !== "M_TERMS_NOT_SIGNED") {
                 throw e;
             }
         }

src/components/structures/FilePanel.tsx

@@ -56,7 +56,7 @@ class FilePanel extends React.Component<IProps, IState> {
     // This is used to track if a decrypted event was a live event and should be
     // added to the timeline.
     private decryptingEvents = new Set<string>();
-    public noRoom: boolean;
+    public noRoom = false;
     private card = createRef<HTMLDivElement>();
 
     public state: IState = {

src/components/structures/GenericDropdownMenu.tsx

@@ -125,7 +125,7 @@ export function GenericDropdownMenu<T>({
 }: IProps<T>): JSX.Element {
     const [menuDisplayed, button, openMenu, closeMenu] = useContextMenu<HTMLElement>();
 
-    const selected: GenericDropdownMenuItem<T> | null = options
+    const selected: GenericDropdownMenuItem<T> | undefined = options
         .flatMap((it) => (isGenericDropdownMenuGroup(it) ? [it, ...it.options] : [it]))
         .find((option) => (toKey ? toKey(option.key) === toKey(value) : option.key === value));
     let contextMenuOptions: JSX.Element;

src/components/structures/ScrollPanel.tsx

@@ -181,19 +181,19 @@ export default class ScrollPanel extends React.Component<IProps> {
     private unmounted = false;
     private scrollTimeout?: Timer;
     // Are we currently trying to backfill?
-    private isFilling: boolean;
+    private isFilling = false;
     // Is the current fill request caused by a props update?
     private isFillingDueToPropsUpdate = false;
     // Did another request to check the fill state arrive while we were trying to backfill?
-    private fillRequestWhileRunning: boolean;
+    private fillRequestWhileRunning = false;
     // Is that next fill request scheduled because of a props update?
-    private pendingFillDueToPropsUpdate: boolean;
+    private pendingFillDueToPropsUpdate = false;
-    private scrollState: IScrollState;
+    private scrollState!: IScrollState;
     private preventShrinkingState: IPreventShrinkingState | null = null;
     private unfillDebouncer: number | null = null;
-    private bottomGrowth: number;
+    private bottomGrowth!: number;
-    private minListHeight: number;
+    private minListHeight!: number;
-    private heightUpdateInProgress: boolean;
+    private heightUpdateInProgress = false;
     private divScroll: HTMLDivElement | null = null;
 
     public constructor(props: IProps) {

src/components/structures/auth/CompleteSecurity.tsx

@@ -28,7 +28,7 @@ interface IProps {
 }
 
 interface IState {
-    phase: Phase;
+    phase?: Phase;
     lostKeys: boolean;
 }
 

src/components/structures/auth/Login.tsx

@@ -19,7 +19,7 @@ import classNames from "classnames";
 import { logger } from "matrix-js-sdk/src/logger";
 import { ISSOFlow, LoginFlow, SSOAction } from "matrix-js-sdk/src/@types/auth";
 
-import { _t, _td } from "../../../languageHandler";
+import { _t, _td, UserFriendlyError } from "../../../languageHandler";
 import Login from "../../../Login";
 import { messageForConnectionError, messageForLoginError } from "../../../utils/ErrorUtils";
 import AutoDiscoveryUtils from "../../../utils/AutoDiscoveryUtils";
@@ -110,7 +110,7 @@ type OnPasswordLogin = {
  */
 export default class LoginComponent extends React.PureComponent<IProps, IState> {
     private unmounted = false;
-    private loginLogic: Login;
+    private loginLogic!: Login;
 
     private readonly stepRendererMap: Record<string, () => ReactNode>;
 
@@ -265,7 +265,7 @@ export default class LoginComponent extends React.PureComponent<IProps, IState>
                 logger.error("Problem parsing URL or unhandled error doing .well-known discovery:", e);
 
                 let message = _t("Failed to perform homeserver discovery");
-                if (e.translatedMessage) {
+                if (e instanceof UserFriendlyError && e.translatedMessage) {
                     message = e.translatedMessage;
                 }
 

src/components/structures/auth/SetupEncryptionBody.tsx

@@ -38,7 +38,7 @@ interface IProps {
 }
 
 interface IState {
-    phase: Phase;
+    phase?: Phase;
     verificationRequest: VerificationRequest | null;
     backupInfo: IKeyBackupInfo | null;
     lostKeys: boolean;

src/components/structures/auth/SoftLogout.tsx

@@ -18,6 +18,7 @@ import React, { ChangeEvent, SyntheticEvent } from "react";
 import { logger } from "matrix-js-sdk/src/logger";
 import { Optional } from "matrix-events-sdk";
 import { ISSOFlow, LoginFlow, SSOAction } from "matrix-js-sdk/src/@types/auth";
+import { MatrixError } from "matrix-js-sdk/src/http-api";
 
 import { _t } from "../../../languageHandler";
 import dis from "../../../dispatcher/dispatcher";
@@ -164,7 +165,11 @@ export default class SoftLogout extends React.Component<IProps, IState> {
             credentials = await sendLoginRequest(hsUrl, isUrl, loginType, loginParams);
         } catch (e) {
             let errorText = _t("Failed to re-authenticate due to a homeserver problem");
-            if (e.errcode === "M_FORBIDDEN" && (e.httpStatus === 401 || e.httpStatus === 403)) {
+            if (
+                e instanceof MatrixError &&
+                e.errcode === "M_FORBIDDEN" &&
+                (e.httpStatus === 401 || e.httpStatus === 403)
+            ) {
                 errorText = _t("Incorrect password");
             }
 

src/components/views/auth/InteractiveAuthEntryComponents.tsx

@@ -214,7 +214,7 @@ export class RecaptchaAuthEntry extends React.Component<IRecaptchaAuthEntryProps
 
         let errorText = this.props.errorText;
 
-        let sitePublicKey;
+        let sitePublicKey: string | undefined;
         if (!this.props.stageParams || !this.props.stageParams.public_key) {
             errorText = _t(
                 "Missing captcha public key in homeserver configuration. Please report " +
@@ -224,7 +224,7 @@ export class RecaptchaAuthEntry extends React.Component<IRecaptchaAuthEntryProps
             sitePublicKey = this.props.stageParams.public_key;
         }
 
-        let errorSection;
+        let errorSection: JSX.Element | undefined;
         if (errorText) {
             errorSection = (
                 <div className="error" role="alert">
@@ -235,7 +235,9 @@ export class RecaptchaAuthEntry extends React.Component<IRecaptchaAuthEntryProps
 
         return (
             <div>
-                <CaptchaForm sitePublicKey={sitePublicKey} onCaptchaResponse={this.onCaptchaResponse} />
+                {sitePublicKey && (
+                    <CaptchaForm sitePublicKey={sitePublicKey} onCaptchaResponse={this.onCaptchaResponse} />
+                )}
                 {errorSection}
             </div>
         );

src/components/views/dialogs/ConfirmSpaceUserActionDialog.tsx

@@ -28,7 +28,7 @@ interface IProps extends Omit<BaseProps, "matrixClient" | "children" | "onFinish
     specificLabel: string;
     noneLabel?: string;
     warningMessage?: string;
-    onFinished(success: boolean, reason?: string, rooms?: Room[]): void;
+    onFinished(success?: boolean, reason?: string, rooms?: Room[]): void;
     spaceChildFilter?(child: Room): boolean;
 }
 
@@ -61,7 +61,7 @@ const ConfirmSpaceUserActionDialog: React.FC<IProps> = ({
     return (
         <ConfirmUserActionDialog
             {...props}
-            onFinished={(success: boolean, reason?: string) => {
+            onFinished={(success?: boolean, reason?: string) => {
                 onFinished(success, reason, roomsToLeave);
             }}
             className="mx_ConfirmSpaceUserActionDialog"

src/components/views/dialogs/InfoDialog.tsx

@@ -15,7 +15,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import React, { ReactNode, KeyboardEvent } from "react";
+import React, { ReactNode } from "react";
 import classNames from "classnames";
 
 import { _t } from "../../../languageHandler";
@@ -30,7 +30,7 @@ interface IProps {
     button?: boolean | string;
     hasCloseButton?: boolean;
     fixedWidth?: boolean;
-    onKeyDown?(event: KeyboardEvent): void;
+    onKeyDown?(event: KeyboardEvent | React.KeyboardEvent): void;
     onFinished(): void;
 }
 

src/components/views/dialogs/MessageEditHistoryDialog.tsx

@@ -76,7 +76,7 @@ export default class MessageEditHistoryDialog extends React.PureComponent<IProps
             result = await client.relations(roomId, eventId, RelationType.Replace, EventType.RoomMessage, opts);
         } catch (error) {
             // log if the server returned an error
-            if (error.errcode) {
+            if (error instanceof MatrixError && error.errcode) {
                 logger.error("fetching /relations failed with error", error);
             }
             this.setState({ error: error as MatrixError }, () => reject(error));

src/components/views/dialogs/ServerPickerDialog.tsx

@@ -20,7 +20,7 @@ import { logger } from "matrix-js-sdk/src/logger";
 
 import AutoDiscoveryUtils from "../../../utils/AutoDiscoveryUtils";
 import BaseDialog from "./BaseDialog";
-import { _t } from "../../../languageHandler";
+import { _t, UserFriendlyError } from "../../../languageHandler";
 import AccessibleButton from "../elements/AccessibleButton";
 import SdkConfig from "../../../SdkConfig";
 import Field from "../elements/Field";
@@ -113,7 +113,7 @@ export default class ServerPickerDialog extends React.PureComponent<IProps, ISta
                 const stateForError = AutoDiscoveryUtils.authComponentStateForError(e);
                 if (stateForError.serverErrorIsFatal) {
                     let error = _t("Unable to validate homeserver");
-                    if (e.translatedMessage) {
+                    if (e instanceof UserFriendlyError && e.translatedMessage) {
                         error = e.translatedMessage;
                     }
                     return { error };

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

@@ -54,12 +54,13 @@ export const stateKeyField = (defaultValue?: string): IFieldDef => ({
 });
 
 const validateEventContent = withValidation<any, Error | undefined>({
-    deriveData({ value }) {
+    async deriveData({ value }) {
         try {
             JSON.parse(value!);
         } catch (e) {
-            return e;
+            return e as Error;
         }
+        return undefined;
     },
     rules: [
         {

src/components/views/dialogs/security/SetupEncryptionDialog.tsx

@@ -21,7 +21,7 @@ import BaseDialog from "../BaseDialog";
 import { _t } from "../../../../languageHandler";
 import { SetupEncryptionStore, Phase } from "../../../../stores/SetupEncryptionStore";
 
-function iconFromPhase(phase: Phase): string {
+function iconFromPhase(phase?: Phase): string {
     if (phase === Phase.Done) {
         return require("../../../../../res/img/e2e/verified-deprecated.svg").default;
     } else {

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

@@ -21,17 +21,7 @@ import { IHierarchyRoom } from "matrix-js-sdk/src/@types/spaces";
 import { IPublicRoomsChunkRoom, MatrixClient, RoomMember, RoomType } from "matrix-js-sdk/src/matrix";
 import { Room } from "matrix-js-sdk/src/models/room";
 import { normalize } from "matrix-js-sdk/src/utils";
-import React, {
+import React, { ChangeEvent, RefObject, useCallback, useContext, useEffect, useMemo, useRef, useState } from "react";
-    ChangeEvent,
-    KeyboardEvent,
-    RefObject,
-    useCallback,
-    useContext,
-    useEffect,
-    useMemo,
-    useRef,
-    useState,
-} from "react";
 import sanitizeHtml from "sanitize-html";
 
 import { KeyBindingAction } from "../../../../accessibility/KeyboardShortcuts";
@@ -1067,7 +1057,7 @@ const SpotlightDialog: React.FC<IProps> = ({ initialText = "", initialFilter = n
         );
     }
 
-    const onDialogKeyDown = (ev: KeyboardEvent): void => {
+    const onDialogKeyDown = (ev: KeyboardEvent | React.KeyboardEvent): void => {
         const navigationAction = getKeyBindingsManager().getNavigationAction(ev);
         switch (navigationAction) {
             case KeyBindingAction.FilterRooms:
@@ -1139,7 +1129,7 @@ const SpotlightDialog: React.FC<IProps> = ({ initialText = "", initialFilter = n
         }
     };
 
-    const onKeyDown = (ev: KeyboardEvent): void => {
+    const onKeyDown = (ev: React.KeyboardEvent): void => {
         const action = getKeyBindingsManager().getAccessibilityAction(ev);
 
         switch (action) {

src/components/views/elements/AppPermission.tsx

@@ -38,7 +38,7 @@ interface IProps {
 }
 
 interface IState {
-    roomMember: RoomMember;
+    roomMember: RoomMember | null;
     isWrapped: boolean;
     widgetDomain: string | null;
 }
@@ -56,7 +56,7 @@ export default class AppPermission extends React.Component<IProps, IState> {
 
         // The second step is to find the user's profile so we can show it on the prompt
         const room = MatrixClientPeg.get().getRoom(this.props.roomId);
-        let roomMember;
+        let roomMember: RoomMember | null = null;
         if (room) roomMember = room.getMember(this.props.creatorUserId);
 
         // Set all this into the initial state

src/components/views/elements/AppTile.tsx

@@ -126,7 +126,7 @@ export default class AppTile extends React.Component<IProps, IState> {
     private persistKey: string;
     private sgWidget: StopGapWidget | null;
     private dispatcherRef?: string;
-    private unmounted: boolean;
+    private unmounted = false;
 
     public constructor(props: IProps) {
         super(props);

src/components/views/elements/Field.tsx

@@ -14,7 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import React, { InputHTMLAttributes, SelectHTMLAttributes, TextareaHTMLAttributes, RefObject } from "react";
+import React, { InputHTMLAttributes, SelectHTMLAttributes, TextareaHTMLAttributes, RefObject, createRef } from "react";
 import classNames from "classnames";
 import { debounce } from "lodash";
 
@@ -118,7 +118,7 @@ interface IState {
 
 export default class Field extends React.PureComponent<PropShapes, IState> {
     private readonly id: string;
-    private inputRef: RefObject<HTMLInputElement | HTMLSelectElement | HTMLTextAreaElement>;
+    private readonly _inputRef = createRef<HTMLInputElement | HTMLSelectElement | HTMLTextAreaElement>();
 
     public static readonly defaultProps = {
         element: "input",
@@ -228,6 +228,10 @@ export default class Field extends React.PureComponent<PropShapes, IState> {
         return valid;
     }
 
+    private get inputRef(): RefObject<HTMLInputElement | HTMLSelectElement | HTMLTextAreaElement> {
+        return this.props.inputRef ?? this._inputRef;
+    }
+
     public render(): React.ReactNode {
         /* eslint @typescript-eslint/no-unused-vars: ["error", { "ignoreRestSiblings": true }] */
         const {
@@ -249,8 +253,6 @@ export default class Field extends React.PureComponent<PropShapes, IState> {
             ...inputProps
         } = this.props;
 
-        this.inputRef = inputRef || React.createRef();
-
         // Handle displaying feedback on validity
         let fieldTooltip: JSX.Element | undefined;
         if (tooltipContent || this.state.feedback) {

src/components/views/elements/InteractiveTooltip.tsx

@@ -302,7 +302,7 @@ interface IState {
  * tooltip along one edge of the target.
  */
 export default class InteractiveTooltip extends React.Component<IProps, IState> {
-    private target: HTMLElement;
+    private target?: HTMLElement;
 
     public static defaultProps = {
         side: Direction.Top,
@@ -345,6 +345,7 @@ export default class InteractiveTooltip extends React.Component<IProps, IState>
 
     private onLeftOfTarget(): boolean {
         const { contentRect } = this.state;
+        if (!this.target) return false;
         const targetRect = this.target.getBoundingClientRect();
 
         if (this.props.direction === Direction.Left) {
@@ -359,6 +360,7 @@ export default class InteractiveTooltip extends React.Component<IProps, IState>
 
     private aboveTarget(): boolean {
         const { contentRect } = this.state;
+        if (!this.target) return false;
         const targetRect = this.target.getBoundingClientRect();
 
         if (this.props.direction === Direction.Top) {
@@ -378,7 +380,7 @@ export default class InteractiveTooltip extends React.Component<IProps, IState>
     private onMouseMove = (ev: MouseEvent): void => {
         const { clientX: x, clientY: y } = ev;
         const { contentRect } = this.state;
-        if (!contentRect) return;
+        if (!contentRect || !this.target) return;
         const targetRect = this.target.getBoundingClientRect();
 
         let direction: Direction;
@@ -423,6 +425,8 @@ export default class InteractiveTooltip extends React.Component<IProps, IState>
             return null;
         }
 
+        if (!this.target) return null;
+
         const targetRect = this.target.getBoundingClientRect();
 
         // The window X and Y offsets are to adjust position when zoomed in to page

src/components/views/rooms/BasicMessageComposer.tsx

@@ -107,7 +107,7 @@ interface IProps {
     initialCaret?: DocumentOffset;
     disabled?: boolean;
 
-    onChange?(selection: Caret, inputType?: string, diff?: IDiff): void;
+    onChange?(selection?: Caret, inputType?: string, diff?: IDiff): void;
     onPaste?(event: ClipboardEvent<HTMLDivElement>, model: EditorModel): boolean;
 }
 
@@ -130,7 +130,7 @@ export default class BasicMessageEditor extends React.Component<IProps, IState>
     private isIMEComposing = false;
     private hasTextSelected = false;
 
-    private _isCaretAtEnd: boolean;
+    private _isCaretAtEnd = false;
     private lastCaret: DocumentOffset;
     private lastSelection: ReturnType<typeof cloneSelection> | null = null;
 
@@ -230,7 +230,7 @@ export default class BasicMessageEditor extends React.Component<IProps, IState>
         }
     }
 
-    private updateEditorState = (selection: Caret, inputType?: string, diff?: IDiff): void => {
+    private updateEditorState = (selection?: Caret, inputType?: string, diff?: IDiff): void => {
         if (!this.editorRef.current) return;
         renderModel(this.editorRef.current, this.props.model);
         if (selection) {

src/components/views/rooms/MessageComposerButtons.tsx

@@ -39,6 +39,7 @@ import { useDispatcher } from "../../../hooks/useDispatcher";
 import { chromeFileInputFix } from "../../../utils/BrowserWorkarounds";
 import IconizedContextMenu, { IconizedContextMenuOptionList } from "../context_menus/IconizedContextMenu";
 import { EmojiButton } from "./EmojiButton";
+import { filterBoolean } from "../../../utils/arrays";
 import { useSettingValue } from "../../../hooks/useSettings";
 import { ButtonEvent } from "../elements/AccessibleButton";
 
@@ -118,8 +119,8 @@ const MessageComposerButtons: React.FC<IProps> = (props: IProps) => {
         ];
     }
 
-    mainButtons = mainButtons.filter((x: ReactElement) => x);
+    mainButtons = filterBoolean(mainButtons);
-    moreButtons = moreButtons.filter((x: ReactElement) => x);
+    moreButtons = filterBoolean(moreButtons);
 
     const moreOptionsClasses = classNames({
         mx_MessageComposer_button: true,

src/components/views/rooms/RoomSublist.tsx

@@ -313,7 +313,7 @@ export default class RoomSublist extends React.Component<IProps, IState> {
     private onResize = (
         e: MouseEvent | TouchEvent,
         travelDirection: Direction,
-        refToElement: HTMLDivElement,
+        refToElement: HTMLElement,
         delta: ResizeDelta,
     ): void => {
         const newHeight = this.heightAtStart + delta.height;
@@ -329,7 +329,7 @@ export default class RoomSublist extends React.Component<IProps, IState> {
     private onResizeStop = (
         e: MouseEvent | TouchEvent,
         travelDirection: Direction,
-        refToElement: HTMLDivElement,
+        refToElement: HTMLElement,
         delta: ResizeDelta,
     ): void => {
         const newHeight = this.heightAtStart + delta.height;

src/components/views/rooms/SearchBar.tsx

@@ -27,7 +27,7 @@ import SearchWarning, { WarningKind } from "../elements/SearchWarning";
 
 interface IProps {
     onCancelClick: () => void;
-    onSearch: (query: string, scope: string) => void;
+    onSearch: (query: string, scope: SearchScope) => void;
     searchInProgress?: boolean;
     isRoomEncrypted?: boolean;
 }

src/components/views/rooms/SendMessageComposer.tsx

@@ -686,7 +686,7 @@ export class SendMessageComposer extends React.Component<ISendMessageComposerPro
         return false;
     };
 
-    private onChange = (selection: Caret, inputType?: string, diff?: IDiff): void => {
+    private onChange = (selection?: Caret, inputType?: string, diff?: IDiff): void => {
         // We call this in here rather than onKeyDown as that would trip it on global shortcuts e.g. Ctrl-k also
         if (!!diff) {
             this.prepareToEncrypt?.();

src/components/views/settings/tabs/user/KeyboardUserSettingsTab.tsx

@@ -31,7 +31,7 @@ interface IKeyboardShortcutRowProps {
 }
 
 // Filter out the labs section if labs aren't enabled.
-const visibleCategories = Object.entries(CATEGORIES).filter(
+const visibleCategories = (Object.entries(CATEGORIES) as [CategoryName, ICategory][]).filter(
     ([categoryName]) => categoryName !== CategoryName.LABS || SdkConfig.get("show_labs_settings"),
 );
 
@@ -73,7 +73,7 @@ const KeyboardUserSettingsTab: React.FC = () => {
     return (
         <div className="mx_SettingsTab mx_KeyboardUserSettingsTab">
             <div className="mx_SettingsTab_heading">{_t("Keyboard")}</div>
-            {visibleCategories.map(([categoryName, category]: [CategoryName, ICategory]) => {
+            {visibleCategories.map(([categoryName, category]) => {
                 return <KeyboardShortcutSection key={categoryName} categoryName={categoryName} category={category} />;
             })}
         </div>

src/editor/dom.ts

@@ -147,7 +147,7 @@ function getTextAndOffsetToNode(
     let foundNode = false;
     let text = "";
 
-    function enterNodeCallback(node: HTMLElement): boolean {
+    function enterNodeCallback(node: Node): boolean {
         if (!foundNode) {
             if (node === selectionNode) {
                 foundNode = true;
@@ -157,7 +157,7 @@ function getTextAndOffsetToNode(
         // but for example while pasting in some browsers, they are still
         // converted to BRs, so also take these into account when they
         // are not the last element in the DIV.
-        if (node.tagName === "BR" && node.nextSibling) {
+        if (node instanceof HTMLElement && node.tagName === "BR" && node.nextSibling) {
             if (!foundNode) {
                 offsetToNode += 1;
             }
@@ -173,12 +173,16 @@ function getTextAndOffsetToNode(
         return true;
     }
 
-    function leaveNodeCallback(node: HTMLElement): void {
+    function leaveNodeCallback(node: Node): void {
         // if this is not the last DIV (which are only used as line containers atm)
         // we don't just check if there is a nextSibling because sometimes the caret ends up
         // after the last DIV and it creates a newline if you type then,
         // whereas you just want it to be appended to the current line
-        if (node.tagName === "DIV" && (<HTMLElement>node.nextSibling)?.tagName === "DIV") {
+        if (
+            node instanceof HTMLElement &&
+            node.tagName === "DIV" &&
+            (<HTMLElement>node.nextSibling)?.tagName === "DIV"
+        ) {
             text += "\n";
             if (!foundNode) {
                 offsetToNode += 1;

src/editor/history.ts

@@ -21,7 +21,7 @@ import { Caret } from "./caret";
 
 export interface IHistory {
     parts: SerializedPart[];
-    caret: Caret;
+    caret?: Caret;
 }
 
 export const MAX_STEP_LENGTH = 10;
@@ -31,7 +31,7 @@ export default class HistoryManager {
     private newlyTypedCharCount = 0;
     private currentIndex = -1;
     private changedSinceLastPush = false;
-    private lastCaret: Caret | null = null;
+    private lastCaret?: Caret;
     private nonWordBoundarySinceLastPush = false;
     private addedSinceLastPush = false;
     private removedSinceLastPush = false;
@@ -41,7 +41,7 @@ export default class HistoryManager {
         this.newlyTypedCharCount = 0;
         this.currentIndex = -1;
         this.changedSinceLastPush = false;
-        this.lastCaret = null;
+        this.lastCaret = undefined;
         this.nonWordBoundarySinceLastPush = false;
         this.addedSinceLastPush = false;
         this.removedSinceLastPush = false;
@@ -85,7 +85,7 @@ export default class HistoryManager {
         }
     }
 
-    private pushState(model: EditorModel, caret: Caret): void {
+    private pushState(model: EditorModel, caret?: Caret): void {
         // remove all steps after current step
         while (this.currentIndex < this.stack.length - 1) {
             this.stack.pop();
@@ -93,7 +93,7 @@ export default class HistoryManager {
         const parts = model.serializeParts();
         this.stack.push({ parts, caret });
         this.currentIndex = this.stack.length - 1;
-        this.lastCaret = null;
+        this.lastCaret = undefined;
         this.changedSinceLastPush = false;
         this.newlyTypedCharCount = 0;
         this.nonWordBoundarySinceLastPush = false;
@@ -102,7 +102,7 @@ export default class HistoryManager {
     }
 
     // needs to persist parts and caret position
-    public tryPush(model: EditorModel, caret: Caret, inputType?: string, diff?: IDiff): boolean {
+    public tryPush(model: EditorModel, caret?: Caret, inputType?: string, diff?: IDiff): boolean {
         // ignore state restoration echos.
         // these respect the inputType values of the input event,
         // but are actually passed in from MessageEditor calling model.reset()

src/hooks/usePublicRoomDirectory.ts

@@ -49,7 +49,7 @@ export const usePublicRoomDirectory = (): {
     publicRooms: IPublicRoomsChunkRoom[];
     protocols: Protocols | null;
     config?: IPublicRoomDirectoryConfig | null;
-    setConfig(config: IPublicRoomDirectoryConfig): void;
+    setConfig(config: IPublicRoomDirectoryConfig | null): void;
     search(opts: IPublicRoomsOpts): Promise<boolean>;
 } => {
     const [publicRooms, setPublicRooms] = useState<IPublicRoomsChunkRoom[]>([]);

src/indexing/EventIndex.ts

@@ -28,6 +28,7 @@ import { logger } from "matrix-js-sdk/src/logger";
 import { EventType } from "matrix-js-sdk/src/@types/event";
 import { ClientEvent, MatrixClient } from "matrix-js-sdk/src/client";
 import { ISyncStateData, SyncState } from "matrix-js-sdk/src/sync";
+import { HTTPError } from "matrix-js-sdk/src/http-api";
 
 import PlatformPeg from "../PlatformPeg";
 import { MatrixClientPeg } from "../MatrixClientPeg";
@@ -471,7 +472,7 @@ export default class EventIndex extends EventEmitter {
                     checkpoint.direction,
                 );
             } catch (e) {
-                if (e.httpStatus === 403) {
+                if (e instanceof HTTPError && e.httpStatus === 403) {
                     logger.log(
                         "EventIndex: Removing checkpoint as we don't have ",
                         "permissions to fetch messages from this room.",
@@ -564,7 +565,7 @@ export default class EventIndex extends EventEmitter {
                 return object;
             });
 
-            let newCheckpoint;
+            let newCheckpoint: ICrawlerCheckpoint | null = null;
 
             // The token can be null for some reason. Don't create a checkpoint
             // in that case since adding it to the db will fail.

src/stores/SetupEncryptionStore.ts

@@ -45,7 +45,7 @@ export enum Phase {
 
 export class SetupEncryptionStore extends EventEmitter {
     private started?: boolean;
-    public phase: Phase;
+    public phase?: Phase;
     public verificationRequest: VerificationRequest | null = null;
     public backupInfo: IKeyBackupInfo | null = null;
     // ID of the key that the secrets we want are encrypted with

src/theme.ts

@@ -145,8 +145,8 @@ function generateCustomFontFaceCSS(faces: IFontFaces[]): string {
                     return "";
                 })
                 .join(", ");
-            const props = Object.keys(face).filter((prop: (typeof allowedFontFaceProps)[number]) =>
+            const props = Object.keys(face).filter((prop) =>
-                allowedFontFaceProps.includes(prop),
+                allowedFontFaceProps.includes(prop as (typeof allowedFontFaceProps)[number]),
             ) as Array<(typeof allowedFontFaceProps)[number]>;
             const body = props
                 .map((prop) => {

src/utils/IdentityServerUtils.ts

@@ -16,6 +16,7 @@ limitations under the License.
 
 import { SERVICE_TYPES } from "matrix-js-sdk/src/service-types";
 import { logger } from "matrix-js-sdk/src/logger";
+import { HTTPError } from "matrix-js-sdk/src/http-api";
 
 import SdkConfig from "../SdkConfig";
 import { MatrixClientPeg } from "../MatrixClientPeg";
@@ -39,7 +40,7 @@ export async function doesIdentityServerHaveTerms(fullUrl: string): Promise<bool
         terms = await MatrixClientPeg.get().getTerms(SERVICE_TYPES.IS, fullUrl);
     } catch (e) {
         logger.error(e);
-        if (e.cors === "rejected" || e.httpStatus === 404) {
+        if (e.cors === "rejected" || (e instanceof HTTPError && e.httpStatus === 404)) {
             terms = null;
         } else {
             throw e;

src/utils/Timer.ts

@@ -14,6 +14,8 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
+import { IDeferred, defer } from "matrix-js-sdk/src/utils";
+
 /**
 A countdown timer, exposing a promise api.
 A timer starts in a non-started state,
@@ -28,9 +30,7 @@ a new one through `clone()` or `cloneIfRun()`.
 export default class Timer {
     private timerHandle?: number;
     private startTs?: number;
-    private promise: Promise<void>;
+    private deferred!: IDeferred<void>;
-    private resolve: () => void;
-    private reject: (err: Error) => void;
 
     public constructor(private timeout: number) {
         this.setNotStarted();
@@ -39,10 +39,8 @@ export default class Timer {
     private setNotStarted(): void {
         this.timerHandle = undefined;
         this.startTs = undefined;
-        this.promise = new Promise<void>((resolve, reject) => {
+        this.deferred = defer();
-            this.resolve = resolve;
+        this.deferred.promise = this.deferred.promise.finally(() => {
-            this.reject = reject;
-        }).finally(() => {
             this.timerHandle = undefined;
         });
     }
@@ -51,7 +49,7 @@ export default class Timer {
         const now = Date.now();
         const elapsed = now - this.startTs!;
         if (elapsed >= this.timeout) {
-            this.resolve();
+            this.deferred.resolve();
             this.setNotStarted();
         } else {
             const delta = this.timeout - elapsed;
@@ -108,7 +106,7 @@ export default class Timer {
     public abort(): Timer {
         if (this.isRunning()) {
             clearTimeout(this.timerHandle);
-            this.reject(new Error("Timer was aborted."));
+            this.deferred.reject(new Error("Timer was aborted."));
             this.setNotStarted();
         }
         return this;
@@ -120,7 +118,7 @@ export default class Timer {
      *@return {Promise}
      */
     public finished(): Promise<void> {
-        return this.promise;
+        return this.deferred.promise;
     }
 
     public isRunning(): boolean {

src/utils/beacon/useOwnLiveBeacons.ts

@@ -65,7 +65,7 @@ export const useOwnLiveBeacons = (liveBeaconIds: BeaconIdentifier[]): LiveBeacon
 
     // select the beacon with latest expiry to display expiry time
     const beacon = liveBeaconIds
-        .map((beaconId) => OwnBeaconStore.instance.getBeaconById(beaconId))
+        .map((beaconId) => OwnBeaconStore.instance.getBeaconById(beaconId)!)
         .sort(sortBeaconsByLatestExpiry)
         .shift();
 

test/editor/mock.ts

@@ -82,12 +82,12 @@ export function createPartCreator(completions: PillPart[] = []) {
 }
 
 export function createRenderer() {
-    const render = (c: Caret) => {
+    const render = (c?: Caret) => {
         render.caret = c;
         render.count += 1;
     };
     render.count = 0;
-    render.caret = null as unknown as Caret;
+    render.caret = null as unknown as Caret | undefined;
     return render;
 }
 

test/editor/position-test.ts

@@ -15,18 +15,7 @@ limitations under the License.
 */
 
 import EditorModel from "../../src/editor/model";
-import { createPartCreator } from "./mock";
+import { createPartCreator, createRenderer } from "./mock";
-import { Caret } from "../../src/editor/caret";
-
-function createRenderer() {
-    const render = (c: Caret) => {
-        render.caret = c;
-        render.count += 1;
-    };
-    render.count = 0;
-    render.caret = null;
-    return render;
-}
 
 describe("editor/position", function () {
     it("move first position backward in empty model", function () {

test/stores/SetupEncryptionStore-test.ts

@@ -48,8 +48,8 @@ describe("SetupEncryptionStore", () => {
         client.bootstrapCrossSigning.mockImplementation(async (opts: IBootstrapCrossSigningOpts) => {
             await opts?.authUploadDeviceSigningKeys?.(makeRequest);
         });
-        mocked(accessSecretStorage).mockImplementation(async (func: () => Promise<void>) => {
+        mocked(accessSecretStorage).mockImplementation(async (func?: () => Promise<void>) => {
-            await func();
+            await func!();
         });
 
         await setupEncryptionStore.resetConfirm();