Flutter go_router结合Provider传Auth数据报实例成员访问错误

项目中采用Provider方案实现状态管理，需要将Auth鉴权提供者的状态信息共享给go_router路由包，实现用户登录状态持久化保持。
根组件中Provider注册的核心代码如下：

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MultiProvider(
        providers: [
          ChangeNotifierProvider(
            create: (ctx) => Auth(),
          ),
         ListenableProxyProvider<Auth, AppRouter>(
            update: (_, authObj, prevOrders) =>
               AppRouter(authObj)
          ),
        ]
      // 省略剩余MaterialApp相关配置
    );
  }
}

AppRouter类中定义了构造方法接收传入的Auth鉴权数据，初始路由配置代码如下：

class AppRouter with ChangeNotifier {
  final Auth authData;
  AppRouter(this.authData);
  final router = GoRouter(
    initialLocation: '/',
    routes: [
      GoRoute(
        name: root,
        path: '/',
        builder: (context, state) => TabsScreen(),
      ),
      GoRoute(
        name: mainScreen,
        path: '/main-screen',
        builder: (context, state) => HomeScreen(),
      ),
      GoRoute(
        name: authscreen,
        path: '/auth-screen',
        builder: (context, state) => AuthScreen(),
      ),
    ],
    redirect: (state) {
      final loginLoc = state.namedLocation(authScreen);
      final loggingIn = state.subloc == loginLoc;
      var loggedIn = authData.isLoggedIn;
      if (!loggedIn && !loggingIn) return loginLoc;
      if (loggedIn && loggingIn) return root;
      return null;
    },
  // 省略剩余路由配置
  );
}

编译阶段抛出如下错误：

The instance member 'authData' can't be accessed in an initializer.
Try replacing the reference to the instance member with a different expression

Dart类实例构造流程中，写在类成员定义位置的字段初始化器执行时机早于构造函数逻辑，此时类实例尚未完成构造，无法访问同实例下的其他成员属性。你在定义router字段时，直接在初始化表达式的redirect回调里引用authData，就会触发该编译错误。
除此之外原写法还有逻辑缺陷：Auth的登录状态变更时，GoRouter无法自动感知变化触发重定向，即使解决编译问题，登录、退出操作后路由也不会自动跳转。

• 将router字段改为late final延迟初始化，把GoRouter的实例化逻辑挪到构造函数中执行，该阶段authData已经完成赋值，可以正常访问。
• 在AppRouter构造函数中监听authData的状态变化，状态变更时调用notifyListeners()，同时给GoRouter传入refreshListenable参数绑定当前AppRouter实例，鉴权状态变化时路由会自动触发redirect逻辑。
• 可选重写dispose方法移除监听，避免内存泄漏。

修复后的AppRouter完整代码如下：

class AppRouter with ChangeNotifier {
  final Auth authData;
  late final GoRouter router;

  AppRouter(this.authData) {
    // 监听鉴权状态变化，通知路由刷新
    authData.addListener(notifyListeners);

    // 构造函数执行阶段authData已完成初始化，可正常访问
    router = GoRouter(
      initialLocation: '/',
      // 绑定刷新监听，状态变化时自动执行重定向
      refreshListenable: this,
      routes: [
        GoRoute(
          name: root,
          path: '/',
          builder: (context, state) => TabsScreen(),
        ),
        GoRoute(
          name: mainScreen,
          path: '/main-screen',
          builder: (context, state) => HomeScreen(),
        ),
        GoRoute(
          name: authscreen,
          path: '/auth-screen',
          builder: (context, state) => AuthScreen(),
        ),
      ],
      redirect: (state) {
        final loginLoc = state.namedLocation(authScreen);
        final loggingIn = state.subloc == loginLoc;
        final loggedIn = authData.isLoggedIn;
        if (!loggedIn && !loggingIn) return loginLoc;
        if (loggedIn && loggingIn) return state.namedLocation(root);
        return null;
      },
    );
  }

  @override
  void dispose() {
    authData.removeListener(notifyListeners);
    super.dispose();
  }
}

内容的提问来源于stack exchange，提问作者Behnam