Long story short:
I'm refactoring some type paths, migrating /prop/chest and others to /prop/container/chest etc. The issue is that when I make that change, and then compile, using the undefined type error that appears, in order to then change the type path in the "Pending Map Errors" window, it wipes out my map in DM.
nukes the map file, leaving it as:
"a" = (/turf/black,/area)
(1,1,1) = {"
a
"}