Flutter: Custom Navigator ModalRoute.of does not work properly - flutter

Question

I want to change my selected tabIndex when user uses back button.
So, I edited my willPopScope to get current Route name. I am using
nested navigation. So my application has two navigators.
When I want to get current route name after pop action, It returning to me mainNavigatorKey's routeName.But I give it the coachNavigatorKey context..
Also I can not get the arguments from previous page data is always null.
ModalRoute.of(NavigatorKeys.coachNavigator.currentState!.context)!.settings.arguments;
WillPopScope(
onWillPop: () async {
await NavigatorKeys.coachNavigator.currentState!.maybePop();
var s = ModalRoute.of(NavigatorKeys.coachNavigator.currentState!.context)!.settings.name;
context.read<CoachMainCubit>().setTabIndexByName(s!);
return false;
},
Here is my Custom Navigator..
class CustomNavigator extends StatelessWidget {
final GlobalKey<NavigatorState> navigatorKey;
final List<RouteObserver>? routeObserverList;
final Map<String, WidgetBuilder> routeList;
const CustomNavigator({Key? key, required this.navigatorKey, required this.routeList, this.routeObserverList}) : super(key: key);
#override
Widget build(BuildContext context) {
return Navigator(
key: navigatorKey,
initialRoute: "/",
observers: routeObserverList ?? [],
onGenerateRoute: (settings) {
return MaterialPageRoute(
builder: (BuildContext context) => routeList[settings.name]!(context),
settings: RouteSettings(name: settings.name),
);
},
);
}
}
Here is how I call my nested navigator:
class CoachMainView extends StatelessWidget {
const CoachMainView({Key? key}) : super(key: key);
#override
Widget build(BuildContext context) {
return WillPopScope(
onWillPop: () async {
if (CoolAlertHelper().isLoadingDialogExists()) {
return false;
}
await NavigatorKeys.coachNavigator.currentState!.maybePop();
return false;
},
child: BlocProvider(
create: (context) => CoachMainCubit(context),
child: const CoachMainScreen(),
),
);
}
}
class CoachMainScreen extends StatelessWidget {
const CoachMainScreen({
Key? key,
}) : super(key: key);
#override
Widget build(BuildContext context) {
return Scaffold(
body: buildCustomNavigator(context),
bottomNavigationBar: buildBottomNavigationBar(context),
);
}
Widget buildBottomNavigationBar(BuildContext context) {
return SafeArea(
child: Padding(
padding: EdgeInsets.symmetric(horizontal: context.dynamicWidth(0.002), vertical: context.dynamicHeight(0.000)),
child: BlocSelector<CoachMainCubit, CoachMainState, int>(
selector: (state) {
return context.read<CoachMainCubit>().currentTabIndex;
},
builder: (context, state) {
return buildBottomNavBar(context);
},
),
),
);
}
CustomNavigator buildCustomNavigator(BuildContext context) {
return CustomNavigator(
navigatorKey: NavigatorKeys.coachNavigator,
routeObserverList: [CoachRouteObserver(context)],
routeList: CoachScreenConstants().getCoachRoutes(context),
);
}