unregister scope issue

[ccadieux]

The following code produces this error. Null check operator used on a null value

    GetIt.I.registerLazySingleton<A>(() => A());
    GetIt.I.pushNewScope(scopeName: 'scope');
    if (GetIt.I.isRegistered<A>()) {
      GetIt.I.unregister<A>();
    }

isRegistered checks all scopes but but unregister only uses the current scope. I don't see a way to check if something is registered in the current scope to prevent this issue.

Seems related to #189

[escamoteur]

fixed in next version