When using ProjectE's Swiftwolf Rending Gale Projectile, upon the projectile striking a mob, the game will crash. This is reproducible on both clients and servers.

Steps to reproduce:

1. Install ProjectE (Latest) and Goki Stats (Latest)
2. Launch game and get a Swiftwolf's Rending Gale from ProjectE, and have fuel (coal, or a charged Klein Star) in your inventory.
3. Press R, with the Swiftwolf in hand, to launch a projectile at a mob.
4. Crash.

I believe this happens because GokiStats affects movement in some aspect, and this projectE projectile is supposed to launch mobs into the air / backwards. Movement A + Movement B = Crash ??
crash-2018-09-13_02.03.26-server.txt

Just a quick looks.

From the projectE EntitySWRGProjectile,
it passes a null as attacker. The goki crashes at this point.

I did a quick fix at commit 8eb1d40ecc95205a0cf9803f9019cb1f0b4c0155

Please wait @NanamiArihara to check if this works.

Same with #20