Hub_SwordPvP error

17:26:05 [ERROR] Could not pass event EntityDamageByEntityEvent to Hub_SwordPvP v2.5
org.bukkit.event.EventException
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:305) ~[spigot-1.8.jar:git-Spigot
-c3c767f-33d5de3]
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62) ~[spigot-1.8.jar:git-Spigot-c
3c767f-33d5de3]
        at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:502) [spigot-1.8.jar:git-Spigot
-c3c767f-33d5de3]
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:487) [spigot-1.8.jar:git-Spigot
-c3c767f-33d5de3]
        at org.bukkit.craftbukkit.v1_8_R1.event.CraftEventFactory.callEvent(CraftEventFactory.java:85) [spigot-1.8.
jar:git-Spigot-c3c767f-33d5de3]
        at org.bukkit.craftbukkit.v1_8_R1.event.CraftEventFactory.callEntityDamageEvent(CraftEventFactory.java:538)
 [spigot-1.8.jar:git-Spigot-c3c767f-33d5de3]
        at org.bukkit.craftbukkit.v1_8_R1.event.CraftEventFactory.handleEntityDamageEvent(CraftEventFactory.java:45
1) [spigot-1.8.jar:git-Spigot-c3c767f-33d5de3]
        at org.bukkit.craftbukkit.v1_8_R1.event.CraftEventFactory.handleLivingEntityDamageEvent(CraftEventFactory.j
ava:570) [spigot-1.8.jar:git-Spigot-c3c767f-33d5de3]
        at net.minecraft.server.v1_8_R1.EntityLiving.d(EntityLiving.java:1096) [spigot-1.8.jar:git-Spigot-c3c767f-3
3d5de3]
        at net.minecraft.server.v1_8_R1.EntityHuman.d(EntityHuman.java:860) [spigot-1.8.jar:git-Spigot-c3c767f-33d5
de3]
        at net.minecraft.server.v1_8_R1.EntityLiving.damageEntity(EntityLiving.java:737) [spigot-1.8.jar:git-Spigot
-c3c767f-33d5de3]
        at net.minecraft.server.v1_8_R1.EntityHuman.damageEntity(EntityHuman.java:801) [spigot-1.8.jar:git-Spigot-c
3c767f-33d5de3]
        at net.minecraft.server.v1_8_R1.EntityPlayer.damageEntity(EntityPlayer.java:486) [spigot-1.8.jar:git-Spigot
-c3c767f-33d5de3]
        at net.minecraft.server.v1_8_R1.EntityHuman.attack(EntityHuman.java:1002) [spigot-1.8.jar:git-Spigot-c3c767
f-33d5de3]
        at net.minecraft.server.v1_8_R1.EntityPlayer.attack(EntityPlayer.java:1051) [spigot-1.8.jar:git-Spigot-c3c7
67f-33d5de3]
        at net.minecraft.server.v1_8_R1.PlayerConnection.a(PlayerConnection.java:1312) [spigot-1.8.jar:git-Spigot-c
3c767f-33d5de3]
        at net.minecraft.server.v1_8_R1.PacketPlayInUseEntity.a(SourceFile:52) [spigot-1.8.jar:git-Spigot-c3c767f-3
3d5de3]
        at net.minecraft.server.v1_8_R1.PacketPlayInUseEntity.a(SourceFile:11) [spigot-1.8.jar:git-Spigot-c3c767f-3
3d5de3]
        at net.minecraft.server.v1_8_R1.PacketHandleTask.run(SourceFile:13) [spigot-1.8.jar:git-Spigot-c3c767f-33d5
de3]
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471) [?:1.7.0_75]
        at java.util.concurrent.FutureTask.run(FutureTask.java:262) [?:1.7.0_75]
        at net.minecraft.server.v1_8_R1.MinecraftServer.z(MinecraftServer.java:696) [spigot-1.8.jar:git-Spigot-c3c7
67f-33d5de3]
        at net.minecraft.server.v1_8_R1.DedicatedServer.z(DedicatedServer.java:316) [spigot-1.8.jar:git-Spigot-c3c7
67f-33d5de3]
        at net.minecraft.server.v1_8_R1.MinecraftServer.y(MinecraftServer.java:634) [spigot-1.8.jar:git-Spigot-c3c7
67f-33d5de3]
        at net.minecraft.server.v1_8_R1.MinecraftServer.run(MinecraftServer.java:537) [spigot-1.8.jar:git-Spigot-c3
c767f-33d5de3]
        at java.lang.Thread.run(Thread.java:745) [?:1.7.0_75]
Caused by: java.lang.NullPointerException
        at es.diamontcraft._Drezed_.PvPHub.onDamage(PvPHub.java:338) ~[?:?]
        at sun.reflect.GeneratedMethodAccessor328.invoke(Unknown Source) ~[?:?]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.7.0_75]
        at java.lang.reflect.Method.invoke(Method.java:606) ~[?:1.7.0_75]
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:301) ~[spigot-1.8.jar:git-Spigot
-c3c767f-33d5de3]
        ... 25 more