Hi :D
Your mod is great, and fits perfectly with Overlord mod, so it's why I used it in my modpack..
and so I encounter a problem..
Here it is:

https://pastebin.com/N44i9ym0

Custom npc is completely inoperant, it's impossible to summon a npc with the tool, and this error occurs..
I don't understand error like that, so, I don't know if it's your mod, or custom npc who's cause this issue.. But, because you've recently updated your mod, I come to you first. ^^

As far as I can tell, this is a Custom NPC issue. That particular function isn't doing anything special on my end, yet Custom NPC is somehow throwing an NPE through this call. I'm not sure why since the mod doesn't have visible source code, but I think it'd be best to bring this up with them instead.