GrapplingHook StackTrace

2013-08-25 18:19:37 [SEVERE] Could not pass event CraftItemEvent to GrapplingHook v1.5.5
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.TimedRegisteredListener.callEvent(TimedRegisteredListener.java:30)
 at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:478)
 at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:463)
 at net.minecraft.server.v1_6_R2.PlayerConnection.a(PlayerConnection.java:1399)
 at net.minecraft.server.v1_6_R2.Packet102WindowClick.handle(SourceFile:31)
 at org.spigotmc.netty.NettyNetworkManager.b(NettyNetworkManager.java:230)
 at net.minecraft.server.v1_6_R2.PlayerConnection.e(PlayerConnection.java:116)
 at net.minecraft.server.v1_6_R2.ServerConnection.b(SourceFile:37)
 at org.spigotmc.netty.NettyServerConnection.b(NettyServerConnection.java:125)
 at net.minecraft.server.v1_6_R2.MinecraftServer.t(MinecraftServer.java:592)
 at net.minecraft.server.v1_6_R2.DedicatedServer.t(DedicatedServer.java:239)
 at net.minecraft.server.v1_6_R2.MinecraftServer.s(MinecraftServer.java:481)
 at net.minecraft.server.v1_6_R2.MinecraftServer.run(MinecraftServer.java:413)
 at net.minecraft.server.v1_6_R2.ThreadServerApplication.run(SourceFile:582)
Caused by: java.lang.NullPointerException
 at com.snowgears.grapplinghook.api.HookAPI.isGrapplingHook(HookAPI.java:21)
 at com.snowgears.grapplinghook.GrapplingListener.onPreCraft(GrapplingListener.java:45)
 at sun.reflect.GeneratedMethodAccessor267.invoke(Unknown Source)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
 at java.lang.reflect.Method.invoke(Method.java:606)
 at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:425)
 ... 15 more