[04:52:39] [Server thread/ERROR]: Could not pass event EntityDeathEvent to KillRewards v1.0.3
org.bukkit.event.EventException
	at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:302) ~[craftbukkit.jar:git-Spigot-1649]
	at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62) ~[craftbukkit.jar:git-Spigot-1649]
	at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:514) [craftbukkit.jar:git-Spigot-1649]
	at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:499) [craftbukkit.jar:git-Spigot-1649]
	at org.bukkit.craftbukkit.v1_7_R4.event.CraftEventFactory.callEntityDeathEvent(CraftEventFactory.java:379) [craftbukkit.jar:git-Spigot-1649]
	at net.minecraft.server.v1_7_R4.EntityLiving.die(EntityLiving.java:810) [craftbukkit.jar:git-Spigot-1649]
	at net.minecraft.server.v1_7_R4.EntityCreeper.die(EntityCreeper.java:132) [craftbukkit.jar:git-Spigot-1649]
	at net.minecraft.server.v1_7_R4.EntityLiving.damageEntity(EntityLiving.java:745) [craftbukkit.jar:git-Spigot-1649]
	at net.minecraft.server.v1_7_R4.EntityMonster.damageEntity(EntityMonster.java:48) [craftbukkit.jar:git-Spigot-1649]
	at net.minecraft.server.v1_7_R4.EntityHuman.attack(EntityHuman.java:950) [craftbukkit.jar:git-Spigot-1649]
	at net.minecraft.server.v1_7_R4.PlayerConnection.a(PlayerConnection.java:1204) [craftbukkit.jar:git-Spigot-1649]
	at net.minecraft.server.v1_7_R4.PacketPlayInUseEntity.a(PacketPlayInUseEntity.java:37) [craftbukkit.jar:git-Spigot-1649]
	at net.minecraft.server.v1_7_R4.PacketPlayInUseEntity.handle(PacketPlayInUseEntity.java:49) [craftbukkit.jar:git-Spigot-1649]
	at net.minecraft.server.v1_7_R4.NetworkManager.a(NetworkManager.java:186) [craftbukkit.jar:git-Spigot-1649]
	at net.minecraft.server.v1_7_R4.ServerConnection.c(ServerConnection.java:81) [craftbukkit.jar:git-Spigot-1649]
	at net.minecraft.server.v1_7_R4.MinecraftServer.v(MinecraftServer.java:734) [craftbukkit.jar:git-Spigot-1649]
	at net.minecraft.server.v1_7_R4.DedicatedServer.v(DedicatedServer.java:289) [craftbukkit.jar:git-Spigot-1649]
	at net.minecraft.server.v1_7_R4.MinecraftServer.u(MinecraftServer.java:584) [craftbukkit.jar:git-Spigot-1649]
	at net.minecraft.server.v1_7_R4.MinecraftServer.run(MinecraftServer.java:490) [craftbukkit.jar:git-Spigot-1649]
	at net.minecraft.server.v1_7_R4.ThreadServerApplication.run(SourceFile:628) [craftbukkit.jar:git-Spigot-1649]
Caused by: java.lang.IllegalArgumentException: Illegal group reference: group index is missing
	at java.util.regex.Matcher.appendReplacement(Unknown Source) ~[?:1.8.0_31]
	at java.util.regex.Matcher.replaceAll(Unknown Source) ~[?:1.8.0_31]
	at java.lang.String.replaceAll(Unknown Source) ~[?:1.8.0_31]
	at com.gmail.falistos.KillRewards.KillRewards.sendMessage(KillRewards.java:111) ~[?:?]
	at com.gmail.falistos.KillRewards.KillRewards.onEntityDeath(KillRewards.java:251) ~[?:?]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_31]
	at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_31]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_31]
	at java.lang.reflect.Method.invoke(Unknown Source) ~[?:1.8.0_31]
	at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:298) ~[craftbukkit.jar:git-Spigot-1649]
	... 19 more