Implementing showcaseview in Flutter raises this error and I can't figure out where it's coming from. The code shown below is part of my project:
BuildContext myContext;
  
  initState(){
  WidgetsBinding.instance.addPostFrameCallback((_) {
  Future.delayed(const Duration(milliseconds: 400), () {
    ShowCaseWidget.of(myContext).startShowCase([_timeline_filter]);
  
  });
});
super.initState();
  }