title: Flutter Firebase DocumentReference.set() is not completing
body: <p>My application was writing to Firestore but suddenly stopped working.  When I try to write to Firestore my write method does not complete.  I have made the following simple test method to troubleshoot my problem but can't seem to figure out what is going on:</p>
  <pre><code>//In database.dart
  Future&lt;void&gt; testSet() async {
    final reference = FirebaseFirestore.instance.doc('users/test');
    await reference.set({'TEST': 'Value'});
    print('This is never printing');
  }
  
  //In home_page.dart called via clicking a button
  Future&lt;void&gt; _testSet(context) async {
    final database = Provider.of&lt;Database&gt;(context, listen: false);
    await database.testSet();
  }
  </code></pre>
  <p>I have tried emptying my Firestore Database as well as adding a <code>users</code> collection; however nothing has worked.  Why am I unable to write to Firestore?</p>