Game Crashes When Wolf/Iron Golem Kills Mob

When you have a wolf kill a mob, your game crashes.

Steps to reproduce:

1. Have mob, in this case a pig.
2. Tame a wolf.
3. Hit the pig, wolf will try to kill it.
4. When the pig dies, your game will crash

My crash log is in the attachment.

Description: Ticking entity

java.lang.NullPointerException: Ticking entity
	at ry.a(SourceFile:445)
	at rx.a(SourceFile:833)
	at rx.a(SourceFile:766)
	at vs.a(SourceFile:64)
	at wg.B(SourceFile:296)
	at to.e(SourceFile:121)
	at th.a(SourceFile:129)
	at ry.cd(SourceFile:620)
	at rx.n(SourceFile:1680)
	at ry.n(SourceFile:473)
	at rl.n(SourceFile:134)
	at vs.n(SourceFile:41)
	at wg.n(SourceFile:183)
	at rx.m(SourceFile:1542)
	at ry.m(SourceFile:265)
	at wg.m(SourceFile:198)
	at aho.a(SourceFile:1481)
	at lq.a(SourceFile:719)
	at aho.g(SourceFile:1459)
	at aho.k(SourceFile:1349)
	at lq.k(SourceFile:552)
	at net.minecraft.server.MinecraftServer.D(SourceFile:618)
	at net.minecraft.server.MinecraftServer.C(SourceFile:546)
	at bya.C(SourceFile:154)
	at net.minecraft.server.MinecraftServer.run(SourceFile:450)
	at java.lang.Thread.run(Thread.java:745)