我在Flutter中的Appbar有问题。如何删除屏幕上的额外空间？（黑线）。
截图

的数据

class MainScreen extends StatelessWidget {
  const MainScreen({super.key});

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp.router(
      title: 'Sample',
      localizationsDelegates: const [
        AppLocalizations.delegate,
        GlobalMaterialLocalizations.delegate,
        GlobalWidgetsLocalizations.delegate,
        GlobalCupertinoLocalizations.delegate,
      ],
      supportedLocales: const [
        Locale('en'),
        Locale('pl'),
      ],
      theme: theme,
      routerConfig: router,
    );
  }
}

final GoRouter router = GoRouter(
  initialLocation: "/",
  routes: <RouteBase>[
    GoRoute(
      path: '/',
      builder: (BuildContext context, GoRouterState state) {
        return SomePage(navController: _navController);
      },
      routes: <RouteBase>[
        GoRoute(
          path: 'page1',
          pageBuilder: (BuildContext context, GoRouterState state) => CupertinoPage(child: OtherPage1(navController: _navController)),
        ),
        GoRoute(
          path: 'page2',
          pageBuilder: (BuildContext context, GoRouterState state) => CupertinoPage(child: OtherPage2(navController: _navController)),
        )
      ],
    ),
  ],
);

class SomePage extends StatelessWidget {
  final NavController navController;

  const SomePage({super.key, required this.navController});

  @override
  Widget build(BuildContext context) {
    return MultiBlocProvider(
        providers: [
          /* here is some code, not relevant for this problem */
        ],
        child: DefaultTabController(
          length: 3,
          child: BlocBuilder<CountersCubit, Counters>(
            builder: (blockContext, state) {
              FocusScopeNode currentFocus = FocusScope.of(blockContext);
              return Scaffold(
                appBar: AppBar(
                  leading: IconButton(
                      onPressed: () => { Navigate.back(navController) },
                      icon: const Icon(Icons.arrow_back)),
                  bottom: TabBar(
                    isScrollable: true,
                    indicatorSize: TabBarIndicatorSize.label,
                    indicatorColor: Colors.blue,
                    indicatorWeight: 3.0,
                    tabs: [
                      Tab(
                          text: processTextTabLabel(
                              label: AppLocalizations.of(context)!
                                  .header_view1,
                              counter: state.view1)),
                      Tab(
                          child: badges.Badge(
                        showBadge: false,
                        child: Text(processTextTabLabel(
                            label: AppLocalizations.of(context)!
                                .header_view2,
                            counter: state.view2)),
                      )),
                      Tab(
                          text: processTextTabLabel(
                              label: AppLocalizations.of(context)!
                                  .header_view3,
                              counter: state.view3)),
                    ],
                  ),
                  title: Text(AppLocalizations.of(context)!.header_title),
                ),

                body: TabBarView(
                  children: [
                    View1(navController: navController),
                    View2(navController: navController),
                    View3(navController: navController)
                  ],
                ),
              );
            },
          ),
        ));
  }
}

我试探着：
1.在scaffold容器之前使用SafeArea小部件。
1.设置高度Appbar。
我尝试了五种方法，我发现堆栈溢出和其他网站。所有在这种情况下不工作。
如果我删除Appbar，视图看起来是正确的。