Hi Davo, you are certainly right it appears the function got removed somehow during a merge with our custom code, will have to look into how to merge cleanly to avoid something like this is the future.
For anyone else, there was also an error for another undefined function "move_to_trash()", this has a fix here https://github.com/moodle/moodle/commit/5ca85a1efe7fcab9c989567169506ee4829c2e89 .
Thank you!