anchor.diff:  
     RadarTouchedSpot? _lastTouchedSpot;
   
  +  late bool _validForMouseTracker;
  +
     @override
     void performLayout() {
       size = computeDryLayout(constraints);
  
positive.code: }
  
  /// Renders our RadarChart, also handles hitTest.
  class RenderRadarChart extends RenderBox {
    RenderRadarChart(RadarChartData data, RadarChartData targetData, double textScale,
        RadarTouchCallback? touchCallback)
        : _data = data,
  
negative.code: 
      _touchCallback?.call(response);
    }
  
    @override
    void attach(PipelineOwner owner) {
      super.attach(owner);
      _validForMouseTracker = true;
    }
  
    @override
    void detach() {
      _validForMouseTracker = false;
      super.detach();
    }
  }
  