With some trial-and-error I found it's this mod causing it. Since that mod tries to automatically increase recipe amounts, it's probably got something to do with that process. I'm just guessing though.
I can't reproduce that error. I've tried Avatars with just Marathon Mod Automated, I've tried adding in the whole Angel's and Bob's basic suite of mods. Can you double check that all of your mods are updated, and if you're still having issues I'll need a list of mods that cause this crash.
However, I just tried the following, with no changes to other mods:
Avatar on/Automated Marathon off: No error
Avatar off/Automated Marathon on: No error
Avatar on/Automated Marathon on: Error
Edit: In case you find that errors are to be expected with such a mess of mods, I understand if you're unwilling to see what combination conflicts. Especially since you have difficulty reproducing it yourself as well.