Error

2013-11-09 20:10:36 [SEVERE] Could not pass event EntityDamageByEntityEvent to DynamicDifficulty v1.0.0
org.bukkit.event.EventException
    at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:427)
    at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62)
    at org.bukkit.plugin.TimedRegisteredListener.callEvent(TimedRegisteredListener.java:30)
    at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:478)
    at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:463)
    at org.bukkit.craftbukkit.v1_6_R3.event.CraftEventFactory.callEvent(CraftEventFactory.java:94)
    at org.bukkit.craftbukkit.v1_6_R3.event.CraftEventFactory.callEntityDamageEvent(CraftEventFactory.java:398)
    at org.bukkit.craftbukkit.v1_6_R3.event.CraftEventFactory.handleEntityDamageEvent(CraftEventFactory.java:423)
    at net.minecraft.server.v1_6_R3.EntityLiving.damageEntity(EntityLiving.java:644)
    at net.minecraft.server.v1_6_R3.EntityHuman.damageEntity(EntityHuman.java:720)
    at net.minecraft.server.v1_6_R3.EntityPlayer.damageEntity(EntityPlayer.java:399)
    at net.minecraft.server.v1_6_R3.EntityMonster.m(EntityMonster.java:79)
    at net.minecraft.server.v1_6_R3.EntityZombie.m(EntityZombie.java:189)
    at net.minecraft.server.v1_6_R3.PathfinderGoalMeleeAttack.e(PathfinderGoalMeleeAttack.java:154)
    at net.minecraft.server.v1_6_R3.PathfinderGoalSelector.a(PathfinderGoalSelector.java:104)
    at net.minecraft.server.v1_6_R3.EntityInsentient.bi(EntityInsentient.java:419)
    at net.minecraft.server.v1_6_R3.EntityLiving.c(EntityLiving.java:1421)
    at net.minecraft.server.v1_6_R3.EntityInsentient.c(EntityInsentient.java:306)
    at net.minecraft.server.v1_6_R3.EntityMonster.c(EntityMonster.java:20)
    at net.minecraft.server.v1_6_R3.EntityZombie.c(EntityZombie.java:123)
    at net.minecraft.server.v1_6_R3.EntityLiving.l_(EntityLiving.java:1284)
    at net.minecraft.server.v1_6_R3.EntityInsentient.l_(EntityInsentient.java:150)
    at net.minecraft.server.v1_6_R3.EntityMonster.l_(EntityMonster.java:24)
    at net.minecraft.server.v1_6_R3.EntityZombie.l_(EntityZombie.java:185)
    at net.minecraft.server.v1_6_R3.World.entityJoinedWorld(World.java:1492)
    at net.minecraft.server.v1_6_R3.World.playerJoinedWorld(World.java:1467)
    at net.minecraft.server.v1_6_R3.World.tickEntities(World.java:1336)
    at net.minecraft.server.v1_6_R3.WorldServer.tickEntities(WorldServer.java:517)
    at net.minecraft.server.v1_6_R3.MinecraftServer.t(MinecraftServer.java:583)
    at net.minecraft.server.v1_6_R3.DedicatedServer.t(DedicatedServer.java:240)
    at net.minecraft.server.v1_6_R3.MinecraftServer.s(MinecraftServer.java:493)
    at net.minecraft.server.v1_6_R3.MinecraftServer.run(MinecraftServer.java:425)
    at net.minecraft.server.v1_6_R3.ThreadServerApplication.run(SourceFile:583)
Caused by: java.lang.NullPointerException
    at com.cjmcguire.bukkit.dynamic.DynamicDifficulty.getPlayersMobInfo(DynamicDifficulty.java:203)
    at com.cjmcguire.bukkit.dynamic.monitor.MonitorListener.updateDamagePlayerReceived(MonitorListener.java:163)
    at com.cjmcguire.bukkit.dynamic.monitor.MonitorListener.onEntityDamageByEntityEvent(MonitorListener.java:124)
    at sun.reflect.GeneratedMethodAccessor117.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:425)
    ... 32 more
    at org.bukkit.craftbukkit.v1_6_R3.CraftServer.disablePlugins(CraftServer.java:283)
    at net.minecraft.server.v1_6_R3.MinecraftServer.stop(MinecraftServer.java:361)
    at net.minecraft.server.v1_6_R3.MinecraftServer.run(MinecraftServer.java:457)
    at net.minecraft.server.v1_6_R3.ThreadServerApplication.run(SourceFile:583)