message: Check matrix client exists when stopping
diff: @@ -52,7 +52,9 @@ class ActiveWidgetStore extends EventEmitter {
  }
  stop() {
  + if (MatrixClientPeg.get()) {
  MatrixClientPeg.get().removeListener('RoomState.events', this.onRoomStateEvents);
  + }
  this._capsByWidgetId = {};
  this._widgetMessagingByWidgetId = {};
  this._roomIdByWidgetId = {};
  