fall back to bare userid for local echo profile

src/matrix/room/Room.js

@@ -678,7 +678,7 @@ export class Room extends EventEmitter {
             if (this._roomEncryption) {
                 this._timeline.enableEncryption(this._decryptEntries.bind(this, DecryptionSource.Timeline));
             }
-            await this._timeline.load(this._user, log);
+            await this._timeline.load(this._user, this._summary.data.membership, log);
             return this._timeline;
         });
     }

src/matrix/room/members/RoomMember.js

@@ -23,6 +23,10 @@ export class RoomMember {
         this._data = data;
     }
 
+    static fromUserId(roomId, userId, membership) {
+        return new RoomMember({roomId, userId, membership});
+    }
+
     static fromMemberEvent(roomId, memberEvent) {
         const userId = memberEvent?.state_key;
         if (typeof userId !== "string") {

src/matrix/room/timeline/Timeline.js

@@ -45,10 +45,17 @@ export class Timeline {
     }
 
     /** @package */
-    async load(user, log) {
+    async load(user, membership, log) {
         const txn = await this._storage.readTxn(this._timelineReader.readTxnStores.concat(this._storage.storeNames.roomMembers));
         const memberData = await txn.roomMembers.get(this._roomId, user.id);
-        this._ownMember = new RoomMember(memberData);
+        if (memberData) {
+            this._ownMember = new RoomMember(memberData);
+        } else {
+            // this should never happen, as our own join into the room would have
+            // made us receive our own member event, but just to be on the safe side and not crash,
+            // fall back to bare user id
+            this._ownMember = RoomMember.fromUserId(this._roomId, user.id, membership);
+        }
         // it should be fine to not update the local entries,
         // as they should only populate once the view subscribes to it
         // if they are populated already, the sender profile would be empty