Ok, http://rb.freedroid.org/r/1598/ now addresses this pretty completely, IMHO:

1) If you can save to the map/ directory it allows you to, with no warnings

2) If you can't save to map/ but you can save to ~/.freedroid_rpg, it warns you
at editor start, and when you save. But now it will save there.

3) It you can't save to either map/ or ~/.freedroid_rpg, it warns and pops out a
debug error telling you, and will not allow you to save at all.

So yeah, it gets rid of the crashes and provides graceful failure.