I tested out doing what Cla55clown might have done, and tested it in MC18.
MC does misbehave, and badly.
All it takes is for a user to set the Cover Art folder to the same as the Music folder location. When you try to then change the Cover Art folder to elsewhere, MC moves the entire contents of the currently configured Cover Art folder into the new Cover Art location. All file links are then broken in MC.
MC should not allow setting the Cover Art folder within any folder locations for any of its known Media, and more importantly, it should never allow placing the Cover Art folder within any system folders. It should probably force creating and using a new folder always, for safety. I didn't test this, but I'm sure it would wipe out Windows should I have configured my Cover Art folder to C:\Windows, or Program Files, or an entire drive if configured to store in the root of the drive.
I am entirely surprised to discover that MC doesn't just move what it manages, but moves everything.