Here's a crash log on a minimal modlist: https://pastebin.com/si6gvrp2

Thanks. It seems this mod returns a custom renderer that isn't extending the vanilla LivingEntityRenderer. This is a problem and I would consider it an issue in the animations mod.
However, I can catch the error and make it a log print instead of a crash. And since Tool Belt isn't currently using belts on zombies (you can, but nothing gives zombies a belt by default), it won't really be an issue.
I'll fix as soon as I can, but you should also report it to the other mod so they can hopefully extend LivingEntityRenderer so they don't break compatibility with mods like mine.