I am getting null check operator used on a null value error when using signout function. Basically if i comment this line out // final user = FirebaseAuth.instance.currentUser!; it works fine but the signout doesn’t work. In short, i want my ui to show with signout function.

Error Image
Error Screenshot
Expected Output
Expected output

Code:

import 'package:blood/constants/constants.dart';
import 'package:blood/widgets/badge_list.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:flutter/material.dart';
import 'package:blood/widgets/horizontal_list.dart';

class DonorHome extends StatefulWidget {
  const DonorHome({super.key});

  @override
  State<DonorHome> createState() => _DonorHomeState();
}

class _DonorHomeState extends State<DonorHome> {
  final user = FirebaseAuth.instance.currentUser!;

**  // sign user out**
  void signUserOut() {
    FirebaseAuth.instance.signOut();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: bgPink,
      body: SafeArea(
        child: Padding(
          padding: EdgeInsets.all(25.0),
          child: Column(
            children: [
              Row(
                mainAxisAlignment: MainAxisAlignment.spaceBetween,
                children: [
                  // Hi, User
                  Column(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: [
                      Text(
                        'Hi, User!',
                        style: TextStyle(
                          color: Colors.black,
                          fontSize: 24,
                          fontWeight: FontWeight.bold,
                        ),
                      ),
                      SizedBox(
                        height: 8,
                      ),
                      Text(
                        '11 March 2023',
                        style: TextStyle(
                          color: Colors.black,
                          fontSize: 12,
                        ),
                      ),
                    ],
                  ),

                  // Settings Icon
                  Container(
                    decoration: BoxDecoration(
                      color: darkPink,
                      borderRadius: BorderRadius.circular(12),
                    ),
                    padding: EdgeInsets.all(12),
// **this is the signout button**
                    child: Container(
                      child: IconButton(
                        icon: Icon(
                          Icons.logout,
                          color: Colors.white,
                        ),
                        onPressed: signUserOut,
                      ),
                    ),
                  ),
                ],
              ),

              SizedBox(
                height: 50,
              ),
              // User just donated
              // SingleChildScrollView(
              //     scrollDirection: Axis.horizontal,
              //     child: Row(
              //       children: [
              //         UserDonatedCard(),
              //         UserDonatedCard(),
              //         UserDonatedCard(),
              //         UserDonatedCard(),
              //         UserDonatedCard(),
              //       ],
              //     )),
              SizedBox(
                height: 349,
                child: ListView.builder(
                  scrollDirection: Axis.horizontal,
                  physics: const BouncingScrollPhysics(),
                  itemBuilder: (context, index) {
                    return MyHorizontalList(
                      startColor: 0xfff59da4,
                      endColor: 0xffee6b73,
                      courseHeadline: 'Donated 0 mins ago!',
                      courseTitle: 'Username',
                      courseImage: 'lib/images/man.png',
                    );
                  },
                ),
              ),
              SizedBox(
                height: 10,
              ),
              Divider(
                thickness: 2,
                color: darkPink,
              ),
              SizedBox(
                height: 25,
              ),
              Expanded(
                child: ListView(
                  children: [
                    BadgesTile(
                        imageUrl: 'lib/images/badge1.png',
                        title: 'Rescue Hero',
                        subtitle: 'subtitle'),
                    BadgesTile(
                        imageUrl: 'lib/images/badge1.png',
                        title: 'Rescue Hero',
                        subtitle: 'subtitle'),
                  ],
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }
}

Auth Service.dart file:

import 'package:firebase_auth/firebase_auth.dart';
import 'package:google_sign_in/google_sign_in.dart';

class AuthService {
  signInWithGoogle() async {
    // begin interactive sign in process
    final GoogleSignInAccount? gUser = await GoogleSignIn().signIn();
    // obtain auth details from request
    final GoogleSignInAuthentication gAuth = await gUser!.authentication;
    // create a new credential for user
    final credential = GoogleAuthProvider.credential(
      accessToken: gAuth.accessToken,
      idToken: gAuth.idToken,
    );
    // sign in
    return await FirebaseAuth.instance.signInWithCredential(credential);
  }
}

Please someone help me

I tried hot restart, tried closing emulator and launching again.

>Solution :

this is becuase there is no user signed in.
FirebaseAuth.instance.currentUser!; is returning null.
first sigin the user and the error will be gone