[SEVERE] Could not pass event PlayerItemHeldEvent to GuildsBasic v2.1.6
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 net.minecraft.server.v1_4_5.NetServerHandler.a(NetServerHandler.java:783)
	at net.minecraft.server.v1_4_5.Packet16BlockItemSwitch.handle(SourceFile:27)
	at net.minecraft.server.v1_4_5.NetworkManager.b(NetworkManager.java:290)
	at net.minecraft.server.v1_4_5.NetServerHandler.d(NetServerHandler.java:113)
	at net.minecraft.server.v1_4_5.ServerConnection.b(SourceFile:39)
	at net.minecraft.server.v1_4_5.DedicatedServerConnection.b(SourceFile:30)
	at net.minecraft.server.v1_4_5.MinecraftServer.r(MinecraftServer.java:597)
	at net.minecraft.server.v1_4_5.DedicatedServer.r(DedicatedServer.java:222)
	at net.minecraft.server.v1_4_5.MinecraftServer.q(MinecraftServer.java:493)
	at net.minecraft.server.v1_4_5.MinecraftServer.run(MinecraftServer.java:426)
	at net.minecraft.server.v1_4_5.ThreadServerApplication.run(SourceFile:856)
Caused by: java.lang.IllegalArgumentException: Cannot drop a Null item.
	at org.apache.commons.lang.Validate.notNull(Validate.java:203)
	at org.bukkit.craftbukkit.v1_4_5.CraftWorld.dropItem(CraftWorld.java:284)
	at me.avocardo.guilds.PlayerListener.onPlayerItemHeldEvent(PlayerListener.java:461)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.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)
	... 14 more