error

06:08:06 [SEVERE] Could not pass event EntityDamageByEntityEvent to OtherDrops v2.8-beta5.1
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.SimplePluginManager.fireEvent(SimplePluginManager.java:477)
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:462)
        at org.bukkit.craftbukkit.v1_4_R1.event.CraftEventFactory.callEvent(CraftEventFactory.java:81)
        at org.bukkit.craftbukkit.v1_4_R1.event.CraftEventFactory.callEntityDamageEvent(CraftEventFactory.java:369)
        at org.bukkit.craftbukkit.v1_4_R1.event.CraftEventFactory.handleEntityDamageEvent(CraftEventFactory.java:391)
        at net.minecraft.server.v1_4_R1.EntityLiving.damageEntity(EntityLiving.java:686)
        at net.minecraft.server.v1_4_R1.EntityMonster.damageEntity(EntityMonster.java:39)
        at net.minecraft.server.v1_4_R1.EntitySnowball.a(SourceFile:30)
        at net.minecraft.server.v1_4_R1.EntityProjectile.j_(EntityProjectile.java:158)
        at net.minecraft.server.v1_4_R1.World.entityJoinedWorld(World.java:1332)
        at net.minecraft.server.v1_4_R1.WorldServer.entityJoinedWorld(WorldServer.java:548)
        at net.minecraft.server.v1_4_R1.World.playerJoinedWorld(World.java:1313)
        at net.minecraft.server.v1_4_R1.World.tickEntities(World.java:1191)
        at net.minecraft.server.v1_4_R1.WorldServer.tickEntities(WorldServer.java:445)
        at net.minecraft.server.v1_4_R1.MinecraftServer.r(MinecraftServer.java:580)
        at net.minecraft.server.v1_4_R1.DedicatedServer.r(DedicatedServer.java:224)
        at net.minecraft.server.v1_4_R1.MinecraftServer.q(MinecraftServer.java:494)
        at net.minecraft.server.v1_4_R1.MinecraftServer.run(MinecraftServer.java:427)
        at net.minecraft.server.v1_4_R1.ThreadServerApplication.run(SourceFile:849)
Caused by: java.lang.NullPointerException
        at com.gmail.zariust.otherdrops.subject.CreatureSubject.matches(CreatureSubject.java:114)
        at com.gmail.zariust.otherdrops.subject.CreatureSubject.matches(CreatureSubject.java:97)
        at com.gmail.zariust.otherdrops.event.CustomDrop.isTool(CustomDrop.java:203)
        at com.gmail.zariust.otherdrops.event.CustomDrop.matches(CustomDrop.java:113)
        at com.gmail.zariust.otherdrops.OtherDrops.gatherDrops(OtherDrops.java:319)
        at com.gmail.zariust.otherdrops.OtherDrops.performDrop(OtherDrops.java:194)
        at com.gmail.zariust.otherdrops.listener.OdEntityListener.onEntityDamage(OdEntityListener.java:60)
        at sun.reflect.GeneratedMethodAccessor211.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:601)
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:425)
        ... 20 more