I'm having a confusingly-worded error on worldgen, and Blame does not appear to be showing any info about the crash. Note that I have NotEnoughCrashes installed as well, so I'm not sure if that's affecting the result.

Also, Minecraft does not close after crashing like this, with or without NEC. In fact, it never leaves the loading screen; I have to manually end the task.

I don't know what mod is causing this; I've removed a couple worldgen mods as blind guesses, but this is quickly getting very frustrating.

See attached my log file:
latest.log

Another log, this time with almost all of my biome mods disabled. I'm struggling to keep track of which mods are adding what features, sadly...
latest.log

Can you please remove notenoughcrashes and then get the crash again? Then give me the latest.log file. Notenoughcrashes is crashing trying to show what is crashing and thus, ends up hiding the real crash log

All of these crashes were caused using the same seed and worldgen settings, so it should be the same worldgen feature causing it each time.

That said: I see BetterMineshafts in the stack trace now. Makes me sad; BetterMineshafts is one of my favorites.
latest.log

Removing all of Yung's mods led to successful worldgen.

Looks like it might be something with the furnace or item being set in the furnace within a Better Mineshaft. Have you tried deleting all of Better Mineshaft's configs to see if it is a corrupted config?

If deleting the config doesn't work, I can poke yung's to let him know to check out your log here as that is code it is crashing on cook timer

If it's the cooking timer specifically, then I think I know what the problem is! I have Hot Furnace installed, which changes furnace speed based on the power of the fuel that's inserted. That explains why I haven't run into this issue before--I've never used Hot Furnace and BetterMineshafts at the same time before.

oh. try removing it and if it does resolve the issue, Hot Furnace may want to know about this in case they are blowing up other mods we well

The world generates successfully when loaded with Yung's mods and without Hot Furnace. I've opened up an issue on Hot Furnace's issue tracker. Thanks for your help! I'm closing this issue, since the confusing error message was dealt with (and was caused by NEC, not by Blame).