title: Error: flutter instance of 'future string'?
body: <p>How do I fix it? It is a flutter authentication error.</p>
  
  <blockquote>
    <p>GPT this error: <strong>flutter instance of 'future string'</strong></p>
  </blockquote>
  
  <p>This is the code:</p>
  
  <pre><code>import 'package:firebase_auth/firebase_auth.dart';
  import 'dart:async';
  
  class Auth {
    FirebaseAuth _auth = FirebaseAuth.instance;
  
    Future&lt;String&gt; signIn(String email, String password) async {
      FirebaseUser _user = await _auth.signInWithEmailAndPassword(email: email, password: password);
      return _user != null ? _user.uid : null;
    }
  
    Future&lt;String&gt; currentUser() async {
      FirebaseUser _user = await _auth.currentUser();
      return _user != null ? _user.uid : null;
    }
  
    Future&lt;void&gt; signOut() async {
      return _auth.signOut();
    }
  
    Future&lt;void&gt; resetAccount(String email) async {
      await _auth.sendPasswordResetEmail(email: email);
    }
  }
  </code></pre>