Everytime I place isometrical Mud terrain in the middle of isometrical Asphalt terrain, I get a division by 0 error. I've tested and this error occurs constantly.
I know someone's going to say "so don't do that", but I thought you might want to know.
Guess what? Don't do it. Heimdal hasn't showed any sign of making an effort to fixing a lot of the bugs in Starforge so you're just going to have to deal with it or switch to SCMDraft 2.
Stop advertising SCMDraft2, this is not the right place to do that. He wants support for SF, and you are not helping anyone. Next time I might warn you -.-"
Voyager: Thanks for reporting the bug. You know that SF's isometric terrain is not perfect yet... but the bug might eventually get fixed someday

You can use an alternative editor until it gets fixed (if it does...).
Guess what? There's no rule against me advertising it and like I stated, Heimdal doesn't look like he's going to fix SF anytime soon. So by suggesting to use SCMD2, I am helping him.
I just tried this and it does exist. Also sometimes when I place dirt (it is how I get costal cliffs) it sometimes get a bit of square terrain at the top and I click and I get this error too.
There is a bunch of Isometrical problems in SF that crash (and don't), what I suggest is if you are only using SF is just remember what crashes and what doesn't. I kno with my costal cliff thing I just said, if I start at the top and go down, I never get any problems or even the square terrain covering it.
Or you can just put the terrain and copy it as a brush.