Transient server 502 while uploading a track

[mahlonsmith]

Occasionally while uploading a track, the save "spinner" stops. Can't quite tell if it uploaded successfully or not without reload. (It does not.) Looks like it just doesn't display an error if the backend doesn't reply with a 200.

Rather than reload, just clicking the button again allows it to go through. (Sometimes this takes multiple attempts.)

Endpoint is the POST to /<<album>>/add-song, response error is the "Bad Gateway" from cloudflare.