Error about generic in flutter

gistfile1.dart

typedef bool GeneticFunction<T>(T geneticData, String key);

class CoolType {}


class Component<T> extends StatefulWidget {
  Component({this.data, this.geneticFunc});
  final T data;
  final GeneticFunction<T> geneticFunc;
  void test()
  {
    var testFunc = geneticFunc;
    testFunc(data, "123");
  }

  @override
  _ComponentState<T> createState() {
    return _ComponentState<T>();
  }
}

// Don't mind SingleTickerProviderStateMixin, just simulate my own filter scenario
class _ComponentState<T> extends State<Component>  with SingleTickerProviderStateMixin
{
  @override
  void initState() {
    print("test one");
    var a = widget.geneticFunc;
    print("test two");
    super.initState();
  }
  @override
  Widget build(BuildContext context) {
    return Container(width: 20, height: 20,);
  }
}

// Step 2. Add following widget to build the view, If not build the view, initState will not be called
Component<CoolType>(
  geneticFunc: (CoolType a, String key){
    return false;
  },
)
  
// Step3. See the errors.
I/flutter ( 4677): ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
I/flutter ( 4677): The following assertion was thrown building NotificationListener<KeepAliveNotification>:
I/flutter ( 4677): type '(CoolType, String) => bool' is not a subtype of type '(dynamic, String) => bool'
I/flutter ( 4677): 
I/flutter ( 4677): Either the assertion indicates an error in the framework itself, or we should provide substantially
I/flutter ( 4677): more information in this error message to help you determine and fix the underlying cause.
I/flutter ( 4677): In either case, please report this assertion by filing a bug on GitHub:
I/flutter ( 4677):   https://github.com/flutter/flutter/issues/new?template=BUG.md
I/flutter ( 4677): 
I/flutter ( 4677): When the exception was thrown, this was the stack:
I/flutter ( 4677): #0      _ComponentState.initState