title: Thread 1 Fatal Error Optional Value Swift
body: <pre><code>@IBAction func login(_ sender: Any) {
      guard emailField.text != "", passField.text != "" else {return}
  
      Auth.auth().signIn(withEmail:emailField.text!,password:passField.text!, completion: { (user, error) in
          if let error = error {
              print(error.localizedDescription)
  </code></pre>
  
  <p>I get this error:</p>
  
  <blockquote>
    <p>Thread 1: Fatal error: Unexpectedly found nil while unwrapping an Optional value. </p>
  </blockquote>