Flutter 使用路由时对空值使用的空检查运算符

我正在重构我的应用程序，以支持使用。有一次我需要从使用

home

属性切换到使用

initialRoute

和

routes

。相关代码片段如下所示：

return PlatformApp(
            material: (_, platform) => MaterialAppData(theme: materialThemeData),
            cupertino: (_, platform) => CupertinoAppData(theme: cupertinoTheme),
            onGenerateTitle: (context) {
              return AppLocalizations.of(context).appTitle;
            },
            localizationsDelegates: [
              AppLocalizations.delegate,
              GlobalMaterialLocalizations.delegate,
              GlobalWidgetsLocalizations.delegate,
              GlobalCupertinoLocalizations.delegate,
            ],
            supportedLocales: [
              const Locale('de', ''),
              const Locale('en', ''),
            ],
            initialRoute: '/',
            routes: {
              '/': (context) {
                return MyHomeScreen(title: AppLocalizations.of(context).appTitle);
              },
            },
            // home:MyHomeScreen(title: 'Static Title'),
          );
        }

当我尝试在iOS上运行此操作时，会生成以下错误：

======== Exception caught by widgets library =======================================================
The following _CastError was thrown building Builder(dirty):
Null check operator used on a null value

The relevant error-causing widget was: 
  CupertinoApp file:///Users/user/Development/flutter/.pub-cache/hosted/pub.dartlang.org/flutter_platform_widgets-1.7.1/lib/src/platform_app.dart:673:14
When the exception was thrown, this was the stack: 
#0      _WidgetsAppState._onGenerateRoute.<anonymous closure> (package:flutter/src/widgets/app.dart:1196:48)
#1      CupertinoPageRoute.buildContent (package:flutter/src/cupertino/route.dart:359:55)
#2      CupertinoRouteTransitionMixin.buildPage (package:flutter/src/cupertino/route.dart:227:26)
#3      _ModalScopeState.build.<anonymous closure>.<anonymous closure> (package:flutter/src/widgets/routes.dart:840:53)
#4      Builder.build (package:flutter/src/widgets/basic.dart:7555:48)
...
====================================================================================================

---

@puelo的评论帮助我弄明白了这一点

---

问题是，在初始化过程的早期，我初始化了Firebase应用程序，并根据结果提供了不同的应用程序小部件。如果firebase仍在加载或抛出错误，我会提供一个带有

home

属性集的简单应用程序-这就是问题所在。现在我更改了它，使应用程序始终保持不变，但加载和错误状态由导航来处理。

您的

初始路由的父项是什么？您正在运行的主窗口小部件。@我添加了更多的代码，以便您可以看到更多的上下文。您是否正在离家出走。这很奇怪。我已经追踪到了颤振代码中的bug，它似乎不知怎么地认为
home
是非空的。您是否在重新启动应用程序之前尝试过
flatter clean
，只是为了保持清醒？
Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel stable, 2.0.6, on macOS 11.2.3 20D91 darwin-x64, locale en-CH)
[✓] Android toolchain - develop for Android devices (Android SDK version 30.0.3)
[✓] Xcode - develop for iOS and macOS
[✓] Chrome - develop for the web
[✓] Android Studio (version 4.2)
[✓] Connected device (4 available)

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