[themeSwitch] not applying styles

[alexander-paterson]

I'm using Firefox 129.

When I apply a style or tweak I'm getting an error in the browser console.

The resource from “http://192.168.0.39:9999/undefined/plugin/themeSwitch/assetsundefined” was blocked due to MIME type (“text/html”) mismatch (X-Content-Type-Options: nosniff).