Frontend shows CORS errors when you quit and restart the backend

[ksylvan]

Reproduce by:

./zoom-manage server
./zoom-manage dashboard
./zoom-manage roster

The frontend should show your meeting participants.

Then kill the server (control-c in the terminal window, and close the window), and restart it.

./zoom-manage server

Refresh the frontend dashboard window, and you'll see the lists are empty.

in the dashboard web browser window, use Developer Tools or Inspect to look at the javascript REST calls. You'll see messages like this:

Access to fetch at 'http://localhost:5000/waiting' from origin 'null' has been blocked by CORS policy:
No 'Access-Control-Allow-Origin' header is present on the requested resource. If an opaque response
serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.

While this CORS denial is happening, you can go to the FastAPI Swagger page at http://localhost:5000/docs#/ and you'll see that the endpoints are working.

By quitting your browser (Brave in my case) and restarting it, everything works again.