01:54:39 [SEVERE] Could not pass event CREATURE_SPAWN to DeadMines
java.lang.NullPointerException
        at net.minecraft.server.EntityTypes.a(EntityTypes.java:61)
        at net.minecraft.server.Packet24MobSpawn.<init>(SourceFile:29)
        at net.minecraft.server.EntityTrackerEntry.b(EntityTrackerEntry.java:276
)
        at net.minecraft.server.EntityTrackerEntry.b(EntityTrackerEntry.java:191
)
        at net.minecraft.server.EntityTrackerEntry.scanPlayers(EntityTrackerEntr
y.java:232)
        at net.minecraft.server.EntityTracker.addEntity(EntityTracker.java:97)
        at net.minecraft.server.EntityTracker.track(EntityTracker.java:63)
        at net.minecraft.server.WorldManager.a(WorldManager.java:16)
        at net.minecraft.server.World.c(World.java:913)
        at net.minecraft.server.WorldServer.c(WorldServer.java:161)
        at net.minecraft.server.World.addEntity(World.java:906)
        at net.minecraft.server.World.addEntity(World.java:858)
        at me.DrBoweNur.DeadMines.Util.spawnZombie(Util.java:341)
        at me.DrBoweNur.DeadMines.CreatureSpawnHandler.onCreatureSpawn(CreatureS
pawnHandler.java:94)
        at org.bukkit.plugin.java.JavaPluginLoader$71.execute(JavaPluginLoader.j
ava:756)
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.jav
a:58)
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.j
ava:339)
        at org.bukkit.craftbukkit.event.CraftEventFactory.callCreatureSpawnEvent
(CraftEventFactory.java:242)
        at net.minecraft.server.World.addEntity(World.java:881)
        at net.minecraft.server.SpawnerCreature.spawnEntities(SpawnerCreature.ja
va:129)
        at net.minecraft.server.World.doTick(World.java:1719)
        at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:503)
        at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:414)
        at net.minecraft.server.ThreadServerApplication.run(SourceFile:457)