Flutter-GetX-Navigation: Null check operator error while loading initial screen

Question

I am very new to Dart, and coding in general. I have produced this code after watching tutorials on YouTube. For the most part, I have been able to troubleshoot most of my problems on my own, here I feel I need some help. I wanted to add a BottomNavigationBar. After I set it as the initial root I am getting the following error:-

Null check operator used on a null value

Here it is:-

The code of page with Bottom nav bar is here:-

class LandingPage extends StatelessWidget {
      LandingPage({Key? key}) : super(key: key);
    
      @override
      Widget build(BuildContext context) {
        return GetBuilder<LandingPageController>(
            builder: (controller) {
              return Scaffold(
                body: SafeArea(
                  child:IndexedStack(
                    index: controller.tabIndex,
                    children: const [
                      HomeScreen(),
                      CourseScreen(),
                      ProfileScreen(),
                    ],
    
                  ),
                ),
                bottomNavigationBar: BottomNavigationBar(
    
                  // onTap: Controller.changeTabIndex,
                  // currentIndex: controller.tabIndex,
                  items: const [
                    BottomNavigationBarItem(
                      icon: Icon(Icons.home),
                      label: 'Home',
                      backgroundColor: Color(0xff2AA8A1),
                    ),
                    BottomNavigationBarItem(
                      icon: Icon(Icons.play_arrow),
                      label: 'Course',
                      backgroundColor: Color(0xff2AA8A1),
                    ),
                    BottomNavigationBarItem(
                      icon: Icon(Icons.person_sharp),
                      label: 'Profile',
                      backgroundColor: Color(0xff2AA8A1),
                    ),
                  ],
    
                ), //BottomNavBar().BottomNavigationBar(),
    
              );
            }
        );
      }
    }

My LandingPage Controller:-

        import 'package:get/get.dart';
    
    class LandingPageController extends GetxController {
      var tabIndex = 0;
    
      void changeTabIndex(int index) {
        tabIndex = index;
        update();
      }
    }

here is my initial Screen:-

 _setInitialScreen(User? user) {
if (user == null) {
  Get.offAll(() => LoginScreen());
} else {
  Get.offAll(() => LandingPage());
}

}

Please Help me understand why I am getting this error

Answer 1

Check the value of controller.tabindex value. May be that's where you are getting null.