message: Check for null room in `VisibilityProvider`
  Hopefully fixes
diff: @@ -37,7 +37,11 @@ export class VisibilityProvider {
  await VoipUserMapper.sharedInstance().onNewInvitedRoom(room);
  }
  - public isRoomVisible(room: Room): boolean {
  + public isRoomVisible(room?: Room): boolean {
  + if (!room) {
  + return false;
  + }
  +
  if (
  CallHandler.sharedInstance().getSupportsVirtualRooms() &&
  VoipUserMapper.sharedInstance().isVirtualRoom(room)
  