when printing debug messages in the mailLossDebug mode, do not attempt to access the folder's prettyURL(). this is because prettyURL() searches up the folder's ancestry while trying to discover its family name :)

problem is: on quit, the ancestor nodes might already be invalidated due to the order they were destroyed.

thus, we use folder->idString() instead in the print.. it ain't pretty, but it's safe and does the job.