title: localhost refused to connect for Forge Autodesk Online Viewer
body: <p>i am following the tutorial from this link: <a href="https://forge.autodesk.com/developer/learn/viewer-app/overview" rel="nofollow noreferrer">https://forge.autodesk.com/developer/learn/viewer-app/overview</a></p>
  <p>after i click the <strong>Authorize me!</strong> button, chrome shows localhost refused to connect.</p>
  <p>there is also this message error in my cmd after runnning <code>npm start</code>:</p>
  <pre><code>node:internal/errors:464
      ErrorCaptureStackTrace(err);
      ^
  
  Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
      at new NodeError (node:internal/errors:371:5)
      at ServerResponse.setHeader (node:_http_outgoing:576:11)
      at ServerResponse.header (C:\Users\Jessilyn\walkthrough\node_modules\express\lib\response.js:776:10)
      at ServerResponse.send (C:\Users\Jessilyn\walkthrough\node_modules\express\lib\response.js:170:12)
      at C:\Users\Jessilyn\walkthrough\start.js:137:17
      at processTicksAndRejections (node:internal/process/task_queues:96:5) {
    code: 'ERR_HTTP_HEADERS_SENT'
  </code></pre>
  <p>it loaded for the first attempt. when i tried again, this error happened. i deleted the git clone and restart the process and have been receiving the same results over and over again.</p>
  <p>i don't understand what's going on, would appreciate if you could provide guidance.</p>