why is not defined for the type BuildContext

Question

1. this is code flutter flavor
2. I cannot using context for read ex: context.read(flavorConfiProvider)

var flavorConfigProvider;
  void mainCommand(FlavorConfig config) {
   flavorConfigProvider =  StateProvider((ref) => config);

  runApp(
    ProviderScope(
       child: MyApp()
   ),
  );
 }

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
   final config = context.read(flavorConfigProvider);
    return MaterialApp(
     title:config.state.appTitle,
     theme:config.state.theme,
     home: const MyHomePage(),
   );
  }
}