This happened right as the zombies died. Could it be something Mob-Rebirth is causing?

SlimeKnights/TinkersConstruct#2652

Version 7.0.2 for MC 1.10.2

I doubt it, unless Tinker's is doing something strange, but I'll take a look at it when I get the chance and see if I can reproduce it.

I finally got to do some good troubleshooting with the player this seems to happen with the most. It turned out to be any weapon not just a Tinker's cross bow. So I ended up pulling mob rebirth from the server and it appears to have stopped the crashing.

https://gist.github.com/tgstyle/626730749ce2751e5ce65680c40c1724

Could it be this line in the error report causing it?

"Entity's Vehicle: ERROR NullPointerException: null"

The biome the player is in is a BoP Bog.. It appears to happen most with mobs in water.

This appears to be an issue with Tinkers not checking if the mob has an attribute before applying it. Because the reborn mobs are copies of the old ones, they already have the attributes that tinkers then tries to re-add.