The following StateError was thrown building IconTheme(color: Color(0xdd000000)): Bad state : No element

Question

This issue happens when returning Theme in MaterialApp.router. I think it has something to do with the child property. When I replace the child with a floating widget for example, the red screen and error goes away

The following StateError was thrown building IconTheme(color: Color(0xdd000000)): Bad state : No element

code:

class NnsDapp extends StatelessWidget {
          final HiveBoxes hiveBoxes;
          final WalletRouterDelegate router;
        
          const NnsDapp({Key? key, required this.hiveBoxes, required this.router})
              : super(key: key);
        
          @override
          Widget build(BuildContext context) {
            return HiveBoxesWidget(
              boxes: hiveBoxes,
              child: ICApiManager(
                child: Builder(builder: (context) {
                  return MaterialApp.router(
                    builder: (context, child) {
                      return Theme(
                          data: getTheme(Responsive.isMobile(context)), child: child!);
                    },
                    debugShowCheckedModeBanner: false,
                    routerDelegate: router,
                    routeInformationParser: WalletRouteParser(hiveBoxes, context),
                    title: 'Network Nervous System',
                  );
                }),
              ),
            );
          }
        
          ThemeData getTheme(bool isMobile) {
            return ThemeData(
              primarySwatch: MaterialColor(AppColors.blue500.value, {
                1000: AppColors.blue1000,
                900: AppColors.blue900,
              }),
              textTheme: nnsDappTextTheme(isMobile),
              textButtonTheme: TextButtonThemeData(
                  style: ButtonStyle(
                      textStyle:
                          MaterialStateProperty.all(TextStyle(color: Colors.white)),
                      overlayColor: MaterialStateProperty.all(
                          AppColors.gray400.withOpacity(0.04)))),
            );
          }
        }
    
    
TextTheme nnsDappTextTheme(bool isMobile) {

  return TextTheme(
    headline1: TextStyle(
        fontSize: isMobile ? 32 : 40,
        fontFamily: Fonts.circularBold,
        color: AppColors.gray50,
        fontWeight: FontWeight.w700),)
}