Hi M
I tried to use your plg Bundler but get this error when trying to test with a file path /media/jui/js/jquery.min.js
This the warnings I get on top of Joomla 3.9.11
Warning
JFolder: :files: Path is not a folder. Path: /home/media/plg_system_bundler/js/
Warning: Invalid argument supplied for foreach() in /home/plugins/system/bundler/bundler.php on line 106
Warning: fopen(/home/media/plg_system_bundler/js/push.js): failed to open stream: No such file or directory in /home/plugins/system/bundler/bundler.php on line 112
Warning: fwrite() expects parameter 1 to be resource, bool given in /home/plugins/system/bundler/bundler.php on line 118
Warning: fclose() expects parameter 1 to be resource, bool given in /home/plugins/system/bundler/bundler.php on line 124