Bukkit

I use a mod called Gravesites that produces a chest of items when people die. It places them underground with a Skull on a Stick for a marker.

[16:55:25] [Server thread/ERROR]: Could not pass event PlayerDeathEvent to Mobs v1.7.2 b1
org.bukkit.event.EventException
at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:320) [craftbukkit2991.jar:git-Bukkit-1.7.2-R0.2-14-g15b04d8-b2991jnks]
at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62) [craftbukkit2991.jar:git-Bukkit-1.7.2-R0.2-14-g15b04d8-b2991jnks]
at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:481) [craftbukkit2991.jar:git-Bukkit-1.7.2-R0.2-14-g15b04d8-b2991jnks]
at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:466) [craftbukkit2991.jar:git-Bukkit-1.7.2-R0.2-14-g15b04d8-b2991jnks]
at org.bukkit.craftbukkit.v1_7_R1.event.CraftEventFactory.callPlayerDeathEvent(CraftEventFactory.java:349) [craftbukkit2991.jar:git-Bukkit-1.7.2-R0.2-14-g15b04d8-b2991jnks]
at net.minecraft.server.v1_7_R1.EntityPlayer.die(EntityPlayer.java:368) [craftbukkit2991.jar:git-Bukkit-1.7.2-R0.2-14-g15b04d8-b2991jnks]
at net.minecraft.server.v1_7_R1.EntityLiving.damageEntity(EntityLiving.java:732) [craftbukkit2991.jar:git-Bukkit-1.7.2-R0.2-14-g15b04d8-b2991jnks]
at net.minecraft.server.v1_7_R1.EntityHuman.damageEntity(EntityHuman.java:746) [craftbukkit2991.jar:git-Bukkit-1.7.2-R0.2-14-g15b04d8-b2991jnks]
at net.minecraft.server.v1_7_R1.EntityPlayer.damageEntity(EntityPlayer.java:446) [craftbukkit2991.jar:git-Bukkit-1.7.2-R0.2-14-g15b04d8-b2991jnks]
at org.bukkit.craftbukkit.v1_7_R1.entity.CraftLivingEntity.damage(CraftLivingEntity.java:197) [craftbukkit2991.jar:git-Bukkit-1.7.2-R0.2-14-g15b04d8-b2991jnks]
at com.extrahardmode.features.Physics.whenBlockLands(Physics.java:168) [ExtraHardModev3.4.2.001.jar:?]
at sun.reflect.GeneratedMethodAccessor99.invoke(Unknown Source) [?:?]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) [?:1.7.0_40]
at java.lang.reflect.Method.invoke(Unknown Source) [?:1.7.0_40]
at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:318) [craftbukkit2991.jar:git-Bukkit-1.7.2-R0.2-14-g15b04d8-b2991jnks]
at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62) [craftbukkit2991.jar:git-Bukkit-1.7.2-R0.2-14-g15b04d8-b2991jnks]
at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:481) [craftbukkit2991.jar:git-Bukkit-1.7.2-R0.2-14-g15b04d8-b2991jnks]
at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:466) [craftbukkit2991.jar:git-Bukkit-1.7.2-R0.2-14-g15b04d8-b2991jnks]
at org.bukkit.craftbukkit.v1_7_R1.event.CraftEventFactory.callEntityChangeBlockEvent(CraftEventFactory.java:536) [craftbukkit2991.jar:git-Bukkit-1.7.2-R0.2-14-g15b04d8-b2991jnks]
at org.bukkit.craftbukkit.v1_7_R1.event.CraftEventFactory.callEntityChangeBlockEvent(CraftEventFactory.java:530) [craftbukkit2991.jar:git-Bukkit-1.7.2-R0.2-14-g15b04d8-b2991jnks]
at org.bukkit.craftbukkit.v1_7_R1.event.CraftEventFactory.callEntityChangeBlockEvent(CraftEventFactory.java:526) [craftbukkit2991.jar:git-Bukkit-1.7.2-R0.2-14-g15b04d8-b2991jnks]
at net.minecraft.server.v1_7_R1.EntityFallingBlock.h(EntityFallingBlock.java:99) [craftbukkit2991.jar:git-Bukkit-1.7.2-R0.2-14-g15b04d8-b2991jnks]
at net.minecraft.server.v1_7_R1.World.entityJoinedWorld(World.java:1338) [craftbukkit2991.jar:git-Bukkit-1.7.2-R0.2-14-g15b04d8-b2991jnks]
at net.minecraft.server.v1_7_R1.World.playerJoinedWorld(World.java:1319) [craftbukkit2991.jar:git-Bukkit-1.7.2-R0.2-14-g15b04d8-b2991jnks]
at net.minecraft.server.v1_7_R1.World.tickEntities(World.java:1207) [craftbukkit2991.jar:git-Bukkit-1.7.2-R0.2-14-g15b04d8-b2991jnks]
at net.minecraft.server.v1_7_R1.WorldServer.tickEntities(WorldServer.java:480) [craftbukkit2991.jar:git-Bukkit-1.7.2-R0.2-14-g15b04d8-b2991jnks]
at net.minecraft.server.v1_7_R1.MinecraftServer.u(MinecraftServer.java:637) [craftbukkit2991.jar:git-Bukkit-1.7.2-R0.2-14-g15b04d8-b2991jnks]
at net.minecraft.server.v1_7_R1.DedicatedServer.u(DedicatedServer.java:250) [craftbukkit2991.jar:git-Bukkit-1.7.2-R0.2-14-g15b04d8-b2991jnks]
at net.minecraft.server.v1_7_R1.MinecraftServer.t(MinecraftServer.java:545) [craftbukkit2991.jar:git-Bukkit-1.7.2-R0.2-14-g15b04d8-b2991jnks]
at net.minecraft.server.v1_7_R1.MinecraftServer.run(MinecraftServer.java:457) [craftbukkit2991.jar:git-Bukkit-1.7.2-R0.2-14-g15b04d8-b2991jnks]
at net.minecraft.server.v1_7_R1.ThreadServerApplication.run(SourceFile:617) [craftbukkit2991.jar:git-Bukkit-1.7.2-R0.2-14-g15b04d8-b2991jnks]
Caused by: java.lang.NullPointerException
at eu.sylian.mobs.BukkitListener.playerDies(BukkitListener.java:288) [?:?]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) [?:1.7.0_40]
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) [?:1.7.0_40]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) [?:1.7.0_40]
at java.lang.reflect.Method.invoke(Unknown Source) [?:1.7.0_40]
at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:318) [craftbukkit2991.jar:git-Bukkit-1.7.2-R0.2-14-g15b04d8-b2991jnks]
... 30 more
[16:55:25] [Server thread/INFO]: FritzDavenport died