'CCDED05C' error sometimes when downloading texture packs in Safari

[UnknownShadow200]

In Console, an error about The operation couldn't be completed. Protocol error appears This seems to be a problem with Safari's handling of 304 response returned by some http/2 webservers

To reproduce

1. Join a level with a texture pack hosted on dropbox
2. Wait about 3-5 minutes
3. Do /reload
4. Observe Error CCDED05C: Website denied download or doesn't exist error message appears

Also see https://stackoverflow.com/questions/66209142/safari-fails-to-load-a-cached-resource-when-receiving-a-304-response

This problem can't be detected by the webclient because web browsers deliberately provide very minimal error data in the XmlHttpRequest response.

But maybe just doing the request again might work? need to test

(note: I used mitmproxy to log responses and observed that a 304 was being returned)