ログインするためにfirebaseでユーザーのメールアドレスとパスワードの検証を確認する方法

Firebaseでユーザーのメールアドレスとパスワードの検証を確認して別のページにログインする方法FirebaseのすべてのものとAndroidStudioの依存関係を設定しました

signin.dart：

import 'package:flutter/material.dart';
import 'package:flutter_app/pages/home.dart';
import 'package:firebase_auth/firebase_auth.dart';

class LoginPage extends StatefulWidget {
  @override
  _LoginPageState createState() => new _LoginPageState();
}

class _LoginPageState extends State<LoginPage> {
  String _email, _password;

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(),
      body: Form(
          child: Column(
            children: <Widget>[
              TextFormField(
                decoration: InputDecoration(
                    labelText: 'Email'
                ),
                onSaved: (input) => _email = input,
              ),
              TextFormField(
                decoration: InputDecoration(
                    labelText: 'Password'
                ),
                onSaved: (input) => _password = input,
                obscureText: true,
              ),
              RaisedButton(
                onPressed: loginUser,
                child: Text('Sign in'),
              ),
            ],
          )
      ),
    );
  }

  Future<FirebaseUser> loginUser() async {
    try {
       await FirebaseAuth.instance
          .signInWithEmailAndPassword(email: _email, password: _password);
      Navigator.push(context, MaterialPageRoute(builder: (context) => Home()));
      // since something changed, let's notify the listeners...
    }  catch (e) {
      // throw the Firebase AuthException that we caught
      throw new AuthException(e.code, e.message);
    }
  }
}

それは私にそれを与えます

E/flutter (20243): [ERROR:flutter/lib/ui/ui_dart_state.cc(157)] Unhandled Exception: NoSuchMethodError: Class '_AssertionError' has no instance getter 'code'.
E/flutter (20243): Receiver: Instance of '_AssertionError'
E/flutter (20243): Tried calling: code
E/flutter (20243): #0      Object.noSuchMethod (dart:core-patch/object_patch.dart:53:5)
E/flutter (20243): #1      _LoginPageState.loginUser (package:flutter_app/setup/signin.dart:51:33)
E/flutter (20243): #2      _InkResponseState._handleTap (package:flutter/src/material/ink_well.dart:706:14)
E/flutter (20243): #3      _InkResponseState.build.<anonymous closure> (package:flutter/src/material/ink_well.dart:789:36)
E/flutter (20243): #4      GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:182:24)
E/flutter (20243): #5      TapGestureRecognizer.handleTapUp (package:flutter/src/gestures/tap.dart:486:11)
E/flutter (20243): #6      BaseTapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:264:5)
E/flutter (20243): #7      BaseTapGestureRecognizer.handlePrimaryPointer (package:flutter/src/gestures/tap.dart:199:7)
E/flutter (20243): #8      PrimaryPointerGestureRecognizer.handleEvent (package:flutter/src/gestures/recognizer.dart:467:9)
E/flutter (20243): #9      PointerRouter._dispatch (package:flutter/src/gestures/pointer_router.dart:76:12)
E/flutter (20243): #10     PointerRouter._dispatchEventToRoutes.<anonymous closure> (package:flutter/src/gestures/pointer_router.dart:117:9)

E / flutter（20243）：＃11 _LinkedHashMapMixin.forEach（dart：collection-patch / complex_hash.dart：379：8）E / flutter（20243）：＃12 PointerRouter._dispatchEventToRoutes（package：flutter / src / gestures / pointer_router。ダーツ：115：18）