Singletons not being instantiated properly

[redsuperbat]

This is how i setup my singletons in the main function.

void main() {
  // setup();
  GetIt.I.registerSingleton(() => ThemeService());
  GetIt.I.registerSingleton(() => ImageService());
  GetIt.I.registerSingleton(() => AuthService());
  GetIt.I.registerSingleton(() => WineService());
  GetIt.I.registerSingleton(() => CellarService());
  runApp(RestartWidget(child: MyApp()));
}

This is the error stack

I/flutter ( 5797): ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
I/flutter ( 5797): The following assertion was thrown building FutureBuilder<void>(dirty, state:
I/flutter ( 5797): _FutureBuilderState<void>#ae63d):
I/flutter ( 5797): Object/factory with  type ThemeService is not registered inside GetIt.
I/flutter ( 5797): (Did you accidentally do  GetIt sl=GetIt.instance(); instead of GetIt sl=GetIt.instance;
I/flutter ( 5797): Did you forget to register it?)
I/flutter ( 5797): 'package:get_it/get_it_impl.dart':
I/flutter ( 5797): Failed assertion: line 298 pos 9: 'instanceFactory != null'
I/flutter ( 5797):
I/flutter ( 5797): The relevant error-causing widget was:
I/flutter ( 5797):   FutureBuilder<void>
package:wine_cellar/main.dart:28
I/flutter ( 5797):
I/flutter ( 5797): When the exception was thrown, this was the stack:

Then in app I'm accessing the themeservice however this is what throws the error. The services should have been instantiated already and should not throw the error. Anyone knows why I would really like to know! =)

class App extends StatelessWidget {
  final themeService = GetIt.I<ThemeService>();

  @override
  Widget build(BuildContext context) {
    return StreamBuilder(
      initialData: WineCellarThemes.light,
      stream: themeService.theme$,
      builder: (context, snapshot) => MaterialApp(
        theme: snapshot.data,
        onGenerateRoute: (settings) => Router.generateRoute(settings),
        home: LandingPage(),
      ),
    );
  }
}

[redsuperbat]

The solution was my syntax before the runApp function. Should be

GetIt.I.registerSingleton<ServiceType>(ServiceType())

[escamoteur]

Strange, my reply was not received by Github. But you are exactly right. Always provide the Generic type. then you would have seen a type error in your first approach.