anchor.diff:  
     /// Shows a "disconnected" overlay if the [service.serviceManager] is not currently connected.
     void _handleNoConnection() {
  -    WidgetsBinding.instance.scheduleFrameCallback((_) {
  +    WidgetsBinding.instance!.scheduleFrameCallback((_) {
         if (!_checkLoaded() &&
  -          ModalRoute.of(context).isCurrent &&
  +          ModalRoute.of(context)!.isCurrent &&
             currentDisconnectedOverlay == null) {
           ga.select(
             analytics_constants.devToolsMain,
             analytics_constants.appDisconnected,
           );
  -        Overlay.of(context).insert(_createDisconnectedOverlay());
  +        Overlay.of(context)!.insert(_createDisconnectedOverlay());
   
           addAutoDisposeListener(serviceManager.connectedState, () {
             final connectedState = serviceManager.connectedState.value;
  
positive.code:         ),
        ),
      );
      return currentDisconnectedOverlay;
    }
  
    @override
  
negative.code:   /// change between successive calls.
    bool _checkLoaded() => serviceManager.hasConnection;
  
    OverlayEntry? currentDisconnectedOverlay;
  
    @override
    void initState() {
  