title: Firebase user displayName is null
body: <p>I'm running this code in my react app:</p>
  
  <pre><code>  componentDidMount() {
      modelInstance.addObserver(this);
      modelInstance.getSignInStatus().then((user)=&gt;{
        this.setState({
          userName: user !== false ? user.displayName : "Sign in",
          logged_in: user !== false ? true : false
  
        });
      });
    }
  </code></pre>
  
  <p>And here is modelInstance.getSignInStatus():</p>
  
  <pre><code>  this.getSignInStatus = function () {
      return new Promise((resolve, reject)=&gt;{
        firebase.auth().onAuthStateChanged(function(user){
          if (user){
            resolve(user);
          }
          else {
            resolve(false);
          }
        });
      });
    }
  </code></pre>
  
  <p>What happens is that <code>this.state.userName</code> is set to <code>null</code>, meaning that <code>user.displayName</code> is <code>null</code>. Why is this?</p>