PNG requests return 500 server error

[alpha-tango-kilo]

No PNG icons from the theme are loading for me. Inspecting the requests show 500 errors. Not too sure of the cause here, but I'm inclined to believe it's not my fault as I can replicate the 500 errors doing requests on localhost (see 2nd screenshot trying to wget - I do run a non-standard WebUI port).

qBittorrent's log file doesn't show anything related, and neither do Docker's container logs.

For my setup, I'm using the linuxserver/docker-qbittorrent docker image, and I've mapped /dracula-theme/webui (dracula-theme being the repo root) to /theme as readonly, and then have set the alternative web UI location to be /theme. All files are owned by the container user / abc and are all 777 per the install instructions.

Apologies for the complex (though hopefully fairly easy to reproduce) setup, any pointers on where I might go from here?