I am attempting to make a login screen using firebaseui auth for a single-page web app. I copied firebaseui's sample code to create the login screen:
<script src="/__/firebase/init.js"></script>
<script src="https://cdn.firebase.com/libs/firebaseui/3.0.0/firebaseui.js"></script>
<link type="text/css" rel="stylesheet" href="https://cdn.firebase.com/libs/firebaseui/3.0.0/firebaseui.css" />
  <script type="text/javascript">
  // FirebaseUI config.
  var uiConfig = {
    signInOptions: [
      // Leave the lines as is for the providers you want to offer your users.
      firebase.auth.GoogleAuthProvider.PROVIDER_ID,
      firebase.auth.EmailAuthProvider.PROVIDER_ID
    ]
  };
  // Initialize the FirebaseUI Widget using Firebase.
  var ui = new firebaseui.auth.AuthUI(firebase.auth());
  // The start method will wait until the DOM is loaded.
  ui.start('#firebaseui-auth-container', uiConfig);
</script>
Then I just inserted a
<div id="firebaseui-auth-container'></div>
to load the login screen. The regular firebase stuff loads just fine, but the auth screen doesn't. Here is the error I got:
Uncaught Error: Could not find the FirebaseUI widget element on the page.
I couldn't find this error anywhere else online, and I'm not sure what it means or why it is appearing. What should I do to make the auth screen load?
 
     
    