check on roomId instead of room

Author: toger5

src/components/views/voip/CallPreview.tsx

@@ -142,12 +142,14 @@ export default class CallPreview extends React.Component<IProps, IState> {
         if (newRoomId === oldRoomId) return;
         // The WidgetLayoutStore observer always tracks the currently viewed Room,
         // so we don't end up with multiple observers and know what observer to remove on unmount
-        const newRoom = MatrixClientPeg.get().getRoom(newRoomId);
         const oldRoom = MatrixClientPeg.get().getRoom(oldRoomId);
         if (oldRoom) {
             WidgetLayoutStore.instance.off(WidgetLayoutStore.emissionForRoom(oldRoom), this.updateCalls);
         }
-        WidgetLayoutStore.instance.on(WidgetLayoutStore.emissionForRoom(newRoom), this.updateCalls);
+        const newRoom = MatrixClientPeg.get().getRoom(newRoomId);
+        if (newRoom) {
+            WidgetLayoutStore.instance.on(WidgetLayoutStore.emissionForRoom(newRoom), this.updateCalls);
+        }
 
         const [primaryCall, secondaryCalls] = getPrimarySecondaryCallsForPip(newRoomId);
         this.setState({