How to pass uid and email to shared preference method When signUp in flutter?

I built the google signin and email password signup app using flutter, I want when user log to application then user's "uid" and "email" save in shared preference. In google login I built when login then pass the boolean value and pass uid and email to shared preference. Then when users close app and when reopen then login in home screen and can get uid and email. But when user signup or login using email password then can not pass the boolean value and uid and email to google login shared preference. In below I'll mentioned google login method and email password method.

googlelogin method

// handling google sigin in
  Future handleGoogleSignIn() async {
    final sp = context.read<SignInProvider>();
    final ip = context.read<InternetProvider>();
    await ip.checkInternetConnection();

    if (ip.hasInternet == false) {
      openSnackbar(context, 'Check your Internet connection', Colors.red);
      googleController.reset();
    } else {
      await sp.signInWithGoogle().then((value) {
        if (sp.hasError == true) {
          openSnackbar(context, sp.errorCode.toString(), Colors.white);
          googleController.reset();
        } else {
          // checking whether user exists or not
          sp.checkUserExists().then((value) async {
            if (value == true) {
              // user exists
              await sp.getUserDataFromFirestore(sp.uid).then((value) => sp
                  .saveDataToSharedPreferences()
                  .then((value) => sp.setSignIn().then((value) {
                        googleController.success();
                        handleAfterSignIn();
                      })));
            } else {
              // user does not exist
              sp.saveDataToFirestore().then((value) => sp
                  .saveDataToSharedPreferences()
                  .then((value) => sp.setSignIn().then((value) {
                        googleController.success();
                        handleAfterSignIn();
                      })));
            }
          });
        }
      });
    }
    //login function
  }

saveDataToSharedPreferences method and setSignIn boolean value (it has in a siginprovider class in another file)

class SignInProvider extends ChangeNotifier {
  //instantiate of  firebaseAuth, facebook and google

  final FirebaseAuth firebaseAuth = FirebaseAuth.instance;

  final GoogleSignIn googleSignIn = GoogleSignIn();

  bool _isSignedIn = false;
  bool get isSignedIn => _isSignedIn;

  //hasError, errorCode, provider,uid,email,name,imageUrl
  bool _hasError = false;

  bool get hasError => _hasError;

  String? _errorCode;

  String? get errorCode => _errorCode;

  String? _uid;

  String? get uid => _uid;

  String? _email;

  String? get email => _email;

  SignInProvider() {
    checkSignInUser();
  }

  Future checkSignInUser() async {
    final SharedPreferences s = await SharedPreferences.getInstance();
    _isSignedIn = s.getBool('signed_in') ?? false;
    notifyListeners();
  }

  Future setSignIn() async {
    final SharedPreferences s = await SharedPreferences.getInstance();
    s.setBool('signed_in', true);
    _isSignedIn = true;
    notifyListeners();
  }

  Future saveDataToSharedPreferences() async {
    final SharedPreferences s = await SharedPreferences.getInstance();
    await s.setString('email', _email!);
    await s.setString('uid', _uid!);
    notifyListeners();
  }

  Future getDataFromSharedPreferences() async {
    final SharedPreferences s = await SharedPr开发者_JAVA技巧eferences.getInstance();
    _email = s.getString('email');
    _uid = s.getString('uid');
    notifyListeners();
  }
}

**email password signup**

  void signUp(String email, String password) async {
    if (_formkey.currentState!.validate()) {
      await _auth
          .createUserWithEmailAndPassword(email: email, password: password)
          .saveDataToSharedPreferences()
      .sp.setSignIn()
          .then((value) => {postDetailsToFirestore()})
          .catchError((e) {
        Fluttertoast.showToast(msg: e!.message);
      });
    }
  }

in email password signup has postDetailsToFirestore method

 postDetailsToFirestore() async {
    // calling our fireStore
    //calling our user model
    // sending these values

    FirebaseFirestore firebaseFirestore = FirebaseFirestore.instance;
    User? user = _auth.currentUser;

    UserModel userModel = UserModel();

    if (user != null) {
      //writing all the values
      userModel.email = user?.email;
      userModel.uid = user?.uid;

      await firebaseFirestore
          .collection("users")
          .doc(user?.uid)
          .set(userModel.toMap());

      Fluttertoast.showToast(msg: "Account created successfully ");
      Navigator.pushAndRemoveUntil(
          (context),
          MaterialPageRoute(builder: (context) => HomeScreen()),
          (route) => false);
    

} }

in email password signup I called

these 2 methods but show this error

when signup how to pass uid and emaill to saveDataToSharedPreferences method and pass sp.setSignIn() boolean like as in google signing?