flutter : [firebase_auth/unknown] Given String is empty or null

Question

my code isn't add person to firebase and isn't reach to the user in authentication. But I can't understand why.

1. This part is firebase part.

          final FirebaseAuth _auth = FirebaseAuth.instance;
          final FirebaseFirestore _firestore = FirebaseFirestore.instance;
   
          Future<User?> signIn(String email, String password) async {
              try {
                  var user = await _auth.signInWithEmailAndPassword(
                  email: email, password: password);
                print(email);
                print(password);
                return user.user;
             } catch (e) {
                print(e);
             }
           }
   
         signOut() async {
             return await _auth.signOut();
        } 
   
        Future<User?> createPerson(String email, String password) async {
            try {
                var user = await _auth.createUserWithEmailAndPassword(
                    email: email, password: password);
   
                await _firestore.collection("Person").doc(user.user?.uid).set({
                "email": email,
                "password": password,
            });
            return user.user;
            } catch (e) {
                 print(e);
            }}} ```
   
   
   

2. This part is input field that I received the email.

          final String hintText;
          final IconData icon;
          final ValueChanged<String>? onChanged;
          final TextEditingController? controller;
          const RoundedInputField({
            Key? key,
            this.hintText = "",
            this.icon = Icons.person,
            this.onChanged,
            this.controller,
          }) : super(key: key);

          @override
          Widget build(BuildContext context) {
            return TextFieldContainer(
              child: TextField(
                onChanged: onChanged,
                controller: controller,

3. Password field

        class PasswordField extends StatefulWidget {
          final ValueChanged<String>? onChanged;
          final TextEditingController? controller;
          const PasswordField({
            Key? key,
            this.onChanged, this.controller,
          }) : super(key: key);

          @override


          State<PasswordField> createState() => _PasswordFieldState();
        }

        class _PasswordFieldState extends State<PasswordField> {
           bool _isObscure = true;
           @override
           Widget build(BuildContext context) {
            return TextFieldContainer(
                child: TextField(
                  onChanged: widget.onChanged,
                  obscureText: _isObscure,
                  controller: widget.controller,
                   ...

3. And this is the sign up part where I use email and password input field

         RoundedInputField(
            hintText: "Your Email",
            onChanged: (value) {},
          ),
          PasswordField(
            onChanged: (value) {},
          ),`enter code here`
          RoundedButton(
            text: "SIGNUP",
            press: () {
              _authService
                  .createPerson(_emailController.text, _passwordController.text)
                  .then((value) {
                return Navigator.push(context,
                    MaterialPageRoute(builder: (context) => LoginScreen()));
              });
            },
          ),

I looked some questions and answers but I can't solve this. Please help me.