Using the mod with Bungeecord the players are immediately kicked when opening their inventory.
Here is what the console shows during the error

http://pastebin.com/ka6J3SGT

Yeah a similar bug has been reported with morph. Fixed in version 1.16

Can you link me the 1.16 code? Curious what was done to fix it.

I'll push to git later.

Thanks!

Actually scratch that, you wont see the fix
The version on this repo is 1.15, my next push will be 1.16.1, you'll never get to see 1.16
Basically I just added a null check (because for some reason, some mods like Morph and apparently Bungeecord somehow break entity IDs)
This might still impact the game (NBT not getting synced properly), but I blame that on them. A player should never be null.

Confirmed 1.16.1 fixed bungeecord issues