So ... I have a question. I'm wanting to get websockets working in CloudFlare pages, and I just don't seem to be able to get it to behave. I created a

websocket.ts

endpoint and it almost seems to be setting up

typescript
async function handleSession(request: Request, websocket: WebSocket) {
  websocket.accept();
  websocket.addEventListener('message', async ({ data }) => {
    websocket.send('<div>Some HTML</div>');
  });

  websocket.addEventListener('close', async (evt) => {
    // Handle when a client closes the WebSocket connection
    console.log(evt);
  });
}

export const onRequest: PagesFunction = async ({ request }) => {
  console.log('websocket');
  const upgradeHeader = request.headers.get('Upgrade');
  if (!upgradeHeader || upgradeHeader !== 'websocket') {
    return new Response('Expected Upgrade: websocket', { status: 400 });
  }
  const [client, server] = Object.values(new WebSocketPair());
  await handleSession(request, server);
  return new Response(null, {
    status: 101,
    webSocket: client,
  });
};

I get

websocket
A hanging Promise was canceled. This happens when the worker runtime is waiting for a Promise from JavaScript to resolve, but has detected that the Promise cannot possibly ever resolve because all code and events related to the Promise's I/O context have already finished.
[mf:inf] GET /websocket 500 Internal Server Error (4ms)