[Alneyan]

Welcome Shirahko!

My understanding is that the map generation in the map editor doesn't quite work, especially with mods. (And it may not even work with the vanilla game ; or rather, I think it doesn't let you choose which mod to use if you happen to have several)

At any rate, the map generation in the editor tends to crash more often than not, so you should generate maps within the game itself rather than use the editor for this purpose.