Not sure if I should report here, or..? This is the first time I've bothered reporting a crash. Pastebin.

Crash happened when I tried to make a world. Sorry if I'm missing something; it's 3:51 and as I said, new at this. Anything else you need to see?

Edit: Oh, forgot to check closed issues. It's the Realistic Terrain Gen, isn't it? Apologies.
Edit2: Do I just need to remove one to play, or is there a workaround?

There's nothing I can do about it, so yeah, for now you'll just have to remove one or the other.