Firebaseにデータを入れると、コンソールにエラー表示がでる

Xcodeのコンソールのエラーコードです。シミュレーターが立ち上がって、いきなり出たエラーです。

Failed to fetch default token Error Domain=com.firebase.iid Code=0 "(null)"```

import UIKit
import Firebase

class SignUpVC: UIViewController, UIImagePickerControllerDelegate, UINavigationControllerDelegate {
    
    // MARK: - Properties
    
    var imageSelected = false
    
    let plusPhotoBtn: UIButton = {
        let button = UIButton(type: .system)
        button.setImage(#imageLiteral(resourceName: "plus_photo").withRenderingMode(.alwaysOriginal), for: .normal)
        button.addTarget(self, action: #selector(handleSelectProfilePhoto), for: .touchUpInside)
        return button
    }()
    
    let emailTextField: UITextField = {
        let tf = UITextField()
        tf.placeholder = "Email"
        tf.backgroundColor = UIColor(white: 0, alpha: 0.03)
        tf.borderStyle = .roundedRect
        tf.font = UIFont.systemFont(ofSize: 14)
        tf.addTarget(self, action: #selector(formValidation), for: .editingChanged)
        return tf
    }()
    
    
    let passwordTextField: UITextField = {
        let tf = UITextField()
        tf.placeholder = "password"
        tf.isSecureTextEntry = true
        tf.backgroundColor = UIColor(white: 0, alpha: 0.03)
        tf.borderStyle = .roundedRect
        tf.font = UIFont.systemFont(ofSize: 14)
        tf.addTarget(self, action: #selector(formValidation), for: .editingChanged)
        return tf
    }()
    
    
    let fullNameTextField: UITextField = {
        let tf = UITextField()
        tf.placeholder = "Full Name"
        tf.backgroundColor = UIColor(white: 0, alpha: 0.03)
        tf.borderStyle = .roundedRect
        tf.font = UIFont.systemFont(ofSize: 14)
        return tf
    }()
    
    let usernameTextField: UITextField = {
        let tf = UITextField()
        tf.placeholder = "Username"
        tf.backgroundColor = UIColor(white: 0, alpha: 0.03)
        tf.borderStyle = .roundedRect
        tf.font = UIFont.systemFont(ofSize: 14)
        return tf
    }()
    
    let signUpButton: UIButton = {
        let button = UIButton(type: .system)
        button.setTitle("Sign Up", for: .normal)
        button.setTitleColor(.white, for: .normal)
        button.backgroundColor = UIColor(red: 149/255, green: 204/255, blue: 244/255, alpha: 1)
        button.layer.cornerRadius = 5
        button.isEnabled = false
        button.addTarget(self, action: #selector(handleSignUp), for: .touchUpInside)
        return button
    }()
    
    
    
    let alreadyHaveAccountButton: UIButton = {
        let button = UIButton(type: .system)
        
        let attributedTitle = NSMutableAttributedString(string: "Already have an account?  ",attributes: [NSAttributedString.Key.font: UIFont.systemFont(ofSize: 14), NSAttributedString.Key.foregroundColor: UIColor.lightGray])
        attributedTitle.append(NSAttributedString(string: "Sign In", attributes: [NSAttributedString.Key.font: UIFont.boldSystemFont(ofSize: 14),NSAttributedString.Key.foregroundColor: UIColor(red: 17/255, green: 154/255, blue: 237/255, alpha: 1)]))
        button.addTarget(self, action: #selector(handleShowLogin), for: .touchUpInside)
        button.setAttributedTitle(attributedTitle, for: .normal)
        
        return button
    }()
    
    

    override func viewDidLoad() {
        super.viewDidLoad()
        
        //background color
        view.backgroundColor = .white
        
        
        view.addSubview(plusPhotoBtn)
        plusPhotoBtn.anchor(top: view.topAnchor, left: nil, bottom: nil, right: nil, paddingTop: 40, paddingLeft: 0, paddingBottom: 0, paddingRight: 0, width: 140, height: 140)
        plusPhotoBtn.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
        
        
        configureViewComponets()
        view.addSubview(alreadyHaveAccountButton)
        alreadyHaveAccountButton.anchor(top: nil, left: view.leftAnchor, bottom: view.bottomAnchor, right: view.rightAnchor, paddingTop: 0, paddingLeft: 0, paddingBottom: 0, paddingRight: 0, width: 0, height: 50)
    }
    
    
    // MARK: - Handlers
    
    @objc func handleSelectProfilePhoto() {
        
        // configure image picker
        let imagePicker = UIImagePickerController()
        imagePicker.delegate = self
        imagePicker.allowsEditing = true
        
        // present image picker
        self.present(imagePicker, animated: true, completion: nil)
        
    }
    
    @objc func handleShowLogin(){
        _ = navigationController?.popViewController(animated: true)
    }
    
 
    
    @objc func handleSignUp() {
    
            guard let email = emailTextField.text else { return }
            guard let password = passwordTextField.text else { return }
        
        Auth.auth().createUser(withEmail: email, password: password) { (user, error) in
            
            //handle error
            if let error = error {
                print("Falled to create user with error: ",error.localizedDescription)
                return
            }
            // success
            print("Successfully created user with Firebase")
        }

    }
    
    @objc func formValidation(){
        guard emailTextField.hasText,
              passwordTextField.hasText,
              fullNameTextField.hasText,
              usernameTextField.hasText,
              imageSelected == true else {
        
        
                signUpButton.isEnabled = false
                signUpButton.backgroundColor = UIColor(red: 149/255, green: 204/255, blue: 244/255, alpha: 1)
                return
        }
        
        signUpButton.isEnabled = true
        signUpButton.backgroundColor = UIColor(red: 17/255, green: 154/255, blue: 237/255, alpha: 1)
    }
    
    
    func configureViewComponets(){
        let stackView = UIStackView(arrangedSubviews: [emailTextField, fullNameTextField, usernameTextField, passwordTextField, signUpButton])
        
        stackView.axis = .vertical
        stackView.spacing = 10
        stackView.distribution = .fillEqually
        
        view.addSubview(stackView)
        stackView.anchor(top: plusPhotoBtn.bottomAnchor, left: view.leftAnchor, bottom: nil, right: view.rightAnchor, paddingTop: 24, paddingLeft: 40, paddingBottom: 0, paddingRight: 40, width: 0, height: 240)
    }
    

    

 

}

すいません。どこを抽出したらいいのかわからず、全部のコードを載せました。
loginとsignUpを作ったのですが、signUpのボタンがクリックしても、色の変化がなく、今回はsignUpのコードを載せました。図々しいですが、なぜボタンの色が変わらないか、見当が付く方いらっしゃいましたら、そちらの方も回答お願いしたいです。よろしくお願いします。