title: Is onclose always called after onerror for WebSocket
body: <p>Is it possible that the onerror callback can be called where onclose will not be called immediately after? In other words, is it possible to get a <code>WebSocket</code> error which does not coincide with the connection then being closed? </p>
  
  <p>If it is possible, I would like to test this case. I have a mocked backend which uses node.js and express-ws. What can I do in the backend to trigger the onerror event callback in the front end.</p>