crash if you load the game (that was created without the mod).

The mod Custom Terrain Generation (0.5.0) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event ctg::on_init()
ctg/control.lua:54: attempt to index field 'ctg-remove-default-water' (a nil value)
stack traceback:
ctg/control.lua:54: in function <ctg/control.lua:45>

Thanks for letting me know, this should be fixed in version 0.5.2. The bug was in a function that warns against belatedly adding the mod.

(Unrelated note, I don't see where version 0.5.1 of the mod went to, and I didn't write anything in the changelog for it, so there might be some other changes I have forgotten / overlooked....)