From 49f506cef49e14e6c7b2adec71f0076388e25c56 Mon Sep 17 00:00:00 2001
From: Travis Ralston <travpc@gmail.com>
Date: Fri, 1 Mar 2019 17:18:16 -0700
Subject: [PATCH] More clearly fix issues with room insertion to lists

Instead of having a catch-all insert, try and fix the common cases with a bit more care.
---
 src/stores/RoomListStore.js | 26 ++++++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)

diff --git a/src/stores/RoomListStore.js b/src/stores/RoomListStore.js
index fc140f31e6..78e0659e36 100644
--- a/src/stores/RoomListStore.js
+++ b/src/stores/RoomListStore.js
@@ -429,6 +429,13 @@ class RoomListStore extends Store {
             newList.push(entry);
         }
 
+        if (!pushedEntry && desiredCategoryBoundaryIndex >= 0) {
+            console.warn(`!! Room ${room.roomId} nearly lost: Ran off the end of the list`);
+            console.warn(`!! Inserting at position ${desiredCategoryBoundaryIndex} with category ${category}`);
+            newList.splice(desiredCategoryBoundaryIndex, 0, {room, category});
+            pushedEntry = true;
+        }
+
         return pushedEntry;
     }
 
@@ -477,16 +484,27 @@ class RoomListStore extends Store {
                     room, category, this._state.lists[key], listsClone[key], lastTimestamp);
 
                 if (!pushedEntry) {
-                    // There's some circumstances where the room doesn't fit anywhere, so just
-                    // push the room in. We push it in at the start of the list because the room
-                    // is probably important.
+                    // This should rarely happen: _slotRoomIntoList has several checks which attempt
+                    // to make sure that a room is not lost in the list. If we do lose the room though,
+                    // we shouldn't throw it on the floor and forget about it. Instead, we should insert
+                    // it somewhere. We'll insert it at the top for a couple reasons: 1) it is probably
+                    // an important room for the user and 2) if this does happen, we'd want a bug report.
+                    console.warn(`!! Room ${room.roomId} nearly lost: Failed to find a position`);
+                    console.warn(`!! Inserting at position 0 in the list and flagging as inserted`);
+                    console.warn("!! Additional info: ", {
+                       category,
+                       key,
+                       upToIndex: listsClone[key].length,
+                       expectedCount: this._state.lists[key].length,
+                    });
                     listsClone[key].splice(0, 0, {room, category});
                 }
                 insertedIntoTags.push(key);
             }
         }
 
-        // Double check that we inserted the room in the right places
+        // Double check that we inserted the room in the right places.
+        // There should never be a discrepancy.
         for (const targetTag of targetTags) {
             let count = 0;
             for (const insertedTag of insertedIntoTags) {