MC: 1.12.2
Mod Ver: 5.8.5
Tested in an instance with just forge and this mod, if turned to stone by a cocatrice, items in offhand are just deleted and no longer exist.

In the case where baubles exist, gravestones can pick them up; but the offhand still goes poof.

Replication steps:

1. spawn in new world, get yourself a cocatrice egg and random item for offhand.
2. use the egg and get turned to stone with the item of choice in your offhand
3. break your stone self with a pickaxe, and notice your offhand item is gone
4. cry

I don't know when I'll get around to it, but its clearly because there was no off-hand when the code was written back in ancient times. At least it should be an easier fix than some of the problems with grave/corpse mod compatibility.

Never thought about that, but now that you mention it, it makes sense.

Unfortunately, I'm moving away from modding, so I can't when this will be fixed or if I'll do it or someone else.

I may be able to take a look at this next week.