fixed guardian login edge cases and misleading placeholders on failed loads

lib/state/app/modules/children/child_selection_cubit.dart

@@ -10,7 +10,7 @@ class ChildSelectionCubit extends HydratedCubit<String?> {
 
   void select(String childId) => emit(childId);
 
-  Future<void> reset() async => emit(null);
+  void reset() => emit(null);
 
   @override
   String? fromJson(Map<String, dynamic> json) => json['childId'] as String?;