我正在为我的移动的应用创建身份验证流。我收到错误：“无法在“self.userSession = user”&“.document（.user.uid）”上的范围“”中找到用户“我不确定如何解决此错误。如有任何帮助，将不胜感激！
'

import SwiftUI
import Firebase
import FirebaseCore
import FirebaseAuth
import FirebaseStorage
import FirebaseFirestore
import FirebaseFirestoreSwift

class AuthViewModel: ObservableObject {
    @Published var userSession: FirebaseAuth.User?
    
    init() {
        self.userSession = Auth.auth().currentUser
        
        print("DEBUG: User session is \(self.userSession?.uid)")
    }
    
    func login(withEmail email: String, password: String) {
        Auth.auth().signIn(withEmail: email, password: password) { result, error in
            if let error = error {
                print("DEBUG: Failed to sign in with error \(error.localizedDescription)")
                return
            }
            
            guard let user = result?.user else { return }
            self.userSession = user
            print("DEBUG: Did log user in..")
        }
    }
    
    func register(withEmail email: String, password: String, fullname: String) {
        Auth.auth().createUser(withEmail: email, password: password) { result, error in
            if let error = error {
                print("DEBUG: Failed to register with error \(error.localizedDescription)")
                return
            }
            
            print("DEBUG: Registered user successfully.")
            print("DEBUG: User is \(self.userSession)")
            
            let data = ["email": email,
                        "fullname": fullname,
                        "uid": user.uid]
            
            Firestore.firestore().collection("users")
                .document(user.uid)
                .setData(data) { _ in
                    print("DEBUG: Did upload user data..")
                }
        }
    }
    
    func signOut() {
        // sets user session to nil so we show login view
        userSession = nil
        
        // signs user out on server
        try? Auth.auth().signOut()
    }
}

'
我试过将声明上移到视图模型中，但这导致了另一个错误：“在范围”中找不到结果。