title: Flutter: Error: 'await' can only be used in 'async' or 'async*' methods. even thought the method is async
body: <p>I have this method:</p>
  <pre><code>Future&lt;AppUser&gt; _getUser(String documentId) async {
      var document = await firestore.collection('customers').doc(documentId);
      document.get().then((DocumentSnapshot documentSnapshot) {
            print(documentSnapshot.data());
      });
      AppUser bruceUser = AppUser(userId: 'user006',);
  
      return bruceUser;   
  }
  </code></pre>
  <p>And below it, I have a variable that uses this method:</p>
  <pre><code>AppUser _user = await _getUser(document.id);
  </code></pre>
  <p>However, this returns the following error:</p>
  <pre><code>Error: 'await' can only be used in 'async' or 'async*' methods.
  </code></pre>
  <p>What am I doing wrong here? I don't want to change _user to Future, because it will complicate the code further, so why doesn't the await work?</p>