Remove dead & duplicated code (#11405)

* Remove dead code

* Make dead code happier

* DRY pickle additional data calculation

* Iterate

src/stores/room-list/RoomListStore.ts

@@ -577,10 +577,9 @@ export class RoomListStoreClass extends AsyncStoreWithClient<IState> implements
      * @param {IFilterCondition} filter The filter condition to add.
      */
     public async addFilter(filter: IFilterCondition): Promise<void> {
-        let promise = Promise.resolve();
         filter.on(FILTER_CHANGED, this.onPrefilterUpdated);
         this.prefilterConditions.push(filter);
-        promise = this.recalculatePrefiltering();
+        const promise = this.recalculatePrefiltering();
         promise.then(() => this.updateFn.trigger());
     }
 

src/stores/room-list/SlidingRoomListStore.ts

@@ -399,6 +399,4 @@ export class SlidingRoomListStoreClass extends AsyncStoreWithClient<IState> impl
     }
 
     protected async onAction(payload: ActionPayload): Promise<void> {}
-
-    protected async onDispatchAsync(payload: ActionPayload): Promise<void> {}
 }

src/stores/room-list/algorithms/Algorithm.ts

@@ -90,10 +90,6 @@ export class Algorithm extends EventEmitter {
         return this._stickyRoom ? this._stickyRoom.room : null;
     }
 
-    public get knownRooms(): Room[] {
-        return this.rooms;
-    }
-
     public get hasTagSortingMap(): boolean {
         return !!this.sortAlgorithms;
     }

src/stores/widgets/StopGapWidget.ts

@@ -242,10 +242,6 @@ export class StopGapWidget extends EventEmitter {
         return parsed.toString().replace(/%24/g, "$");
     }
 
-    public get isManagedByManager(): boolean {
-        return !!this.scalarToken;
-    }
-
     public get started(): boolean {
         return !!this.messaging;
     }

src/stores/widgets/StopGapWidgetDriver.ts

@@ -245,7 +245,7 @@ export class StopGapWidgetDriver extends WidgetDriver {
 
         if (!client || !roomId) throw new Error("Not in a room or not attached to a client");
 
-        let r: { event_id: string } | null = null; // eslint-disable-line camelcase
+        let r: { event_id: string } | null;
         if (stateKey !== null) {
             // state event
             r = await client.sendStateEvent(roomId, eventType, content, stateKey);