What caused this?

Not sure what part of my plugin is causing this. Happens 1/10 times and is pretty serious, causing the server to crash. Halp? :c

Plugin: http://dev.bukkit.org/server-mods/discosheepplus/
Source: https://github.com/FlyingPikachu/DiscoSheep-

Code:

2013-04-08 19:45:29 [INFO] Emericasktr1 issued server command: /ds party riipyn
2013-04-08 19:45:30 [SEVERE] net.minecraft.server.v1_5_R2.ReportedException: Ticking entity
2013-04-08 19:45:30 [SEVERE]    at net.minecraft.server.v1_5_R2.MinecraftServer.r(MinecraftServer.java:566)
2013-04-08 19:45:30 [SEVERE]    at net.minecraft.server.v1_5_R2.DedicatedServer.r(DedicatedServer.java:225)
2013-04-08 19:45:30 [SEVERE]    at net.minecraft.server.v1_5_R2.MinecraftServer.q(MinecraftServer.java:476)
2013-04-08 19:45:30 [SEVERE]    at net.minecraft.server.v1_5_R2.MinecraftServer.run(MinecraftServer.java:409)
2013-04-08 19:45:30 [SEVERE]    at net.minecraft.server.v1_5_R2.ThreadServerApplication.run(SourceFile:573)
2013-04-08 19:45:30 [SEVERE] Caused by: java.lang.NullPointerException
2013-04-08 19:45:30 [SEVERE]    at net.minecraft.server.v1_5_R2.Entity.teleportTo(Entity.java:1789)
2013-04-08 19:45:30 [SEVERE]    at net.minecraft.server.v1_5_R2.Entity.c(Entity.java:1782)
2013-04-08 19:45:30 [SEVERE]    at net.minecraft.server.v1_5_R2.BlockEnderPortal.a(BlockEnderPortal.java:47)
2013-04-08 19:45:30 [SEVERE]    at net.minecraft.server.v1_5_R2.Entity.C(Entity.java:749)
2013-04-08 19:45:30 [SEVERE]    at net.minecraft.server.v1_5_R2.Entity.move(Entity.java:701)
2013-04-08 19:45:30 [SEVERE]    at net.minecraft.server.v1_5_R2.EntityLiving.e(EntityLiving.java:1096)
2013-04-08 19:45:30 [SEVERE]    at net.minecraft.server.v1_5_R2.EntityLiving.c(EntityLiving.java:1343)
2013-04-08 19:45:30 [SEVERE]    at net.minecraft.server.v1_5_R2.EntityAgeable.c(EntityAgeable.java:72)
2013-04-08 19:45:30 [SEVERE]    at net.minecraft.server.v1_5_R2.EntityAnimal.c(SourceFile:30)
2013-04-08 19:45:30 [SEVERE]    at net.minecraft.server.v1_5_R2.EntitySheep.c(EntitySheep.java:52)
2013-04-08 19:45:30 [SEVERE]    at net.minecraft.server.v1_5_R2.EntityLiving.l_(EntityLiving.java:542)
2013-04-08 19:45:30 [SEVERE]    at net.minecraft.server.v1_5_R2.World.entityJoinedWorld(World.java:1356)
2013-04-08 19:45:30 [SEVERE]    at net.minecraft.server.v1_5_R2.WorldServer.entityJoinedWorld(WorldServer.java:597)
2013-04-08 19:45:30 [SEVERE]    at net.minecraft.server.v1_5_R2.World.playerJoinedWorld(World.java:1337)
2013-04-08 19:45:30 [SEVERE]    at net.minecraft.server.v1_5_R2.World.tickEntities(World.java:1225)
2013-04-08 19:45:30 [SEVERE]    at net.minecraft.server.v1_5_R2.WorldServer.tickEntities(WorldServer.java:463)
2013-04-08 19:45:30 [SEVERE]    at net.minecraft.server.v1_5_R2.MinecraftServer.r(MinecraftServer.java:562)
2013-04-08 19:45:30 [SEVERE]    ... 4 more
2013-04-08 19:45:30 [SEVERE] Encountered an unexpected exception ReportedException
net.minecraft.server.v1_5_R2.ReportedException: Ticking entity
        at net.minecraft.server.v1_5_R2.MinecraftServer.r(MinecraftServer.java:566)
        at net.minecraft.server.v1_5_R2.DedicatedServer.r(DedicatedServer.java:225)
        at net.minecraft.server.v1_5_R2.MinecraftServer.q(MinecraftServer.java:476)
        at net.minecraft.server.v1_5_R2.MinecraftServer.run(MinecraftServer.java:409)
        at net.minecraft.server.v1_5_R2.ThreadServerApplication.run(SourceFile:573)
Caused by: java.lang.NullPointerException
        at net.minecraft.server.v1_5_R2.Entity.teleportTo(Entity.java:1789)
        at net.minecraft.server.v1_5_R2.Entity.c(Entity.java:1782)
        at net.minecraft.server.v1_5_R2.BlockEnderPortal.a(BlockEnderPortal.java:47)
        at net.minecraft.server.v1_5_R2.Entity.C(Entity.java:749)
        at net.minecraft.server.v1_5_R2.Entity.move(Entity.java:701)
        at net.minecraft.server.v1_5_R2.EntityLiving.e(EntityLiving.java:1096)
        at net.minecraft.server.v1_5_R2.EntityLiving.c(EntityLiving.java:1343)
        at net.minecraft.server.v1_5_R2.EntityAgeable.c(EntityAgeable.java:72)
        at net.minecraft.server.v1_5_R2.EntityAnimal.c(SourceFile:30)
        at net.minecraft.server.v1_5_R2.EntitySheep.c(EntitySheep.java:52)
        at net.minecraft.server.v1_5_R2.EntityLiving.l_(EntityLiving.java:542)
        at net.minecraft.server.v1_5_R2.World.entityJoinedWorld(World.java:1356)
        at net.minecraft.server.v1_5_R2.WorldServer.entityJoinedWorld(WorldServer.java:597)
        at net.minecraft.server.v1_5_R2.World.playerJoinedWorld(World.java:1337)
        at net.minecraft.server.v1_5_R2.World.tickEntities(World.java:1225)
        at net.minecraft.server.v1_5_R2.WorldServer.tickEntities(WorldServer.java:463)
        at net.minecraft.server.v1_5_R2.MinecraftServer.r(MinecraftServer.java:562)
        ... 4 more
2013-04-08 19:45:30 [SEVERE] This crash report has been saved to: /var/games/minecraft/pigcraft_server/./crash-reports/crash-2013-04-08_19.45.30-server.txt

 

Something to do with entity teleportation is null

 

When going through an ender portal.

 

Ya know, I thought that, but I recently put up a similar issue on Leaky about fireworks and ender portals and got shot down. Do you think this could be prevented or should I make another issue?

 

Bump, still looking for fix.