使用提供程序包弹出页面时，获取对 null 值使用的 null 检查运算符-解网

问：

我有一个执行此功能的登录按钮：

static Future loginPress(BuildContext context, TextEditingController emailController, TextEditingController passwordController) async {
    Loader(context);
    try {
      await MyUser.signIn(emailController.text.trim(), passwordController.text.trim());
      Navigator.of(context).pop();
      Navigator.of(context).pushReplacementNamed(Routes.authPage);
        
    } on CustomException catch (e) {
      Navigator.of(context).pop();
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text(e.message.toString()))
      );
    }
    return null;
  }

上面的 Loader 执行以下命令：

Future<dynamic> Loader(BuildContext context) {
  return showDialog(
    context: context, 
    builder: (context){
      return Center(child: CircularProgressIndicator(color: COLOR_PRIMARY),);
    }
  );
}

第一个代码块具有 MyUser.signIn 函数，如下所示：

static Future signIn(String email, String password) async {
    if(email.isEmpty || password.isEmpty) throw CustomException('Either email or password field is empty');
    try {
      await FirebaseAuth.instance.signInWithEmailAndPassword(email: email, password: password);
    } on FirebaseAuthException catch (e) {
      print(e.message);
      throw CustomException('Wrong password or email');
    }
  }


_dirty:false
_hadUnsatisfiedDependencies:false
_inDirtyList:false
_inheritedWidgets:null
_lifecycleState:_ElementLifecycle (_ElementLifecycle.defunct)
_owner:BuildOwner
_parent:null
_slot:null
_state:null
_widget:null
debugDoingBuild:false
debugIsDefunct:true
depth:121
dirty:false
hashCode:138
owner:BuildOwner
renderObject:null
runtimeType:Type (StatefulElement)
size:<Cannot get size of inactive element.
In order for an element to have a valid size, the element must be active, which means it is part of the tree.
Instead, this element is in the _ElementLifecycle.defunct state.
The size getter was called for the following element:
  StatefulElement#0008a(DEFUNCT)
#0      Element.size.<anonymous closure> (package:flutter/src/widgets/framework.dart:4029:9)
#1      Element.size (package:flutter/src/widgets/framework.dart:4062:6)
#2      StatefulElement.Eval ()
#3      AuthViewModel.loginPress (package:better_health/view_model/auth_view_model.dart:49:17)
<asynchronous suspension>>
slot:null
state:<Null check operator used on a null value
#0      StatefulElement.state (package:flutter/src/widgets/framework.dart:4877:44)
#1      StatefulElement.Eval ()
#2      AuthViewModel.loginPress (package:better_health/view_model/auth_view_model.dart:49:17)
<asynchronous suspension>>
widget:<Null check operator used on a null value

在我执行 Navigator.of（context）.pop（）的第一个代码块中，我收到错误 Null check 运算符用于 null 值，但这种情况只偶尔发生。其他时候，它工作正常。我该如何解决这个问题？

颤振 Firebase 飞镖

static Future loginPress(BuildContext context, TextEditingController emailController, TextEditingController passwordController) async {
    late BuildContext dialogContext;
    showDialog(
      context: context, 
      builder: (context) {
        dialogContext = context;
        return Center(child: CircularProgressIndicator(color: COLOR_PRIMARY),);
      }
    );
    try {
      await MyUser.signIn(emailController.text.trim(), passwordController.text.trim());
      Navigator.of(dialogContext).pop();
      Navigator.of(dialogContext).pushReplacementNamed(Routes.authPage);
        
    } on CustomException catch (e) {
      Navigator.of(context).pop();
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text(e.message.toString()))
      );
    }
    return null;
  }

不知道为什么。也许有人可以填补我的空缺。

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使用提供程序包弹出页面时，获取对 null 值使用的 null 检查运算符

Getting null check operator used on a null value when popping page with Provider package

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