title: Oidc-client UserManager is not defined error
body: <p>I'm building an angular 5 application, using Identity Server 3 (Implicit Flow), based off this tutorial:
  <a href="https://www.scottbrady91.com/OpenID-Connect/Silent-Refresh-Refreshing-Access-Tokens-when-using-the-Implicit-Flow" rel="nofollow noreferrer">https://www.scottbrady91.com/OpenID-Connect/Silent-Refresh-Refreshing-Access-Tokens-when-using-the-Implicit-Flow</a>
  (he uses Identity 4)</p>
  
  <p>so far everything is working, except for the silent refresh page's signinSilentCallback call.  My page looks like:</p>
  
  <pre><code>&lt;head&gt;
      &lt;title&gt;&lt;/title&gt;
  &lt;/head&gt;
  &lt;body&gt;
          &lt;script src="https://cdnjs.cloudflare.com/ajax/libs/oidc-client/1.3.0/oidc-client.js"&gt;&lt;/script&gt;
  &lt;script&gt;    
      new UserManager().signinSilentCallback()
          .catch((err) =&gt; {
              console.log(err);
          });
  &lt;/script&gt;
  &lt;/body&gt;
  </code></pre>
  
  <p>I initially was referencing the odic-client.js file directly as his sample, but either way i keep getting the below error:</p>
  
  <blockquote>
    <p>VM861 silent-refresh.html:7 Uncaught ReferenceError: UserManager is not defined
        at VM861 silent-refresh.html:7</p>
  </blockquote>
  
  <p>Not sure what i'm missing, why it can't create a reference to the UserManager object. the .js is loaded, as I see the file in Chrome's network tab.  As soon as the token expires the silent-refresh.html page shows up in the network tab, along with the oidc-client.js file.</p>