Error on remove_purgatory_entry and cleanup_purgatory_dir

Since I upgraded to High Sierra I get this error pair in the system logs a lot:

remove_purgatory_entry:6011: error 2 removing purgatory entry 3/0x4c7bf2-dead for ino 5012466

cleanup_purgatory_dir:16649: *** Cleaning purgatory removed 1 entries but found 1 BAD entries

The bold parts are different every time.

What does is mean?

It only happens on one MacMini Late 2012 in the office.