@darki73 so i figured out your original error, look like it happens if the settings object is missing from folders.json. Why i might not have been there i've got no clue
For me prefs is an array, i remember it turning into an object in the past for me when there was folders loading issues.
You could try Reset sorting or deleting it at "/boot/config/plugins/dockerMan/userprefs.cfg"
Will also include your PR as it still works if prefs is an array so win win
For now a reinstall the plugin achieves the same goal. But yeah would be nice will do