It may be that my dev/js folder structure is not correct:
/dev/js/gameplay.js
I do not have the "front" subfolder that is present with css files. Is this an issue? I have noticed that the docs state:
For example, if we created javascript files in dev/js/front/mygroup/somefile.js, then the bundle name would be front_mygroup.js (location, underscore, groupname), and loaded as follows:
\IPS\Output::i()->jsFiles = array_merge( \IPS\Output::i()->jsFiles, \IPS\Output::i()->js( 'front_mygroup.js', 'app', 'location' ) );
But I am not using the underscored bundle name, I don't think? Maybe I just need to sleep on it, it's been a long day already 🤣