Bukkit

This happens when equip saddle on horse.

[10:38:43 ERROR]: Could not pass event InventoryClickEvent to MCPacks v3.6
org.bukkit.event.EventException
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.ja
va:320) ~[craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.jav
a:62) ~[craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
        at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.j
ava:486) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.j
ava:471) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
        at net.minecraft.server.v1_7_R1.PlayerConnection.a(PlayerConnection.java
:1361) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
        at net.minecraft.server.v1_7_R1.PacketPlayInWindowClick.a(SourceFile:32)
[craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
        at net.minecraft.server.v1_7_R1.PacketPlayInWindowClick.handle(SourceFil
e:10) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
        at net.minecraft.server.v1_7_R1.NetworkManager.a(NetworkManager.java:146
) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
        at net.minecraft.server.v1_7_R1.ServerConnection.c(SourceFile:134) [craf
tbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
        at net.minecraft.server.v1_7_R1.MinecraftServer.u(MinecraftServer.java:6
55) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
        at net.minecraft.server.v1_7_R1.DedicatedServer.u(DedicatedServer.java:2
50) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
        at net.minecraft.server.v1_7_R1.MinecraftServer.t(MinecraftServer.java:5
45) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
        at net.minecraft.server.v1_7_R1.MinecraftServer.run(MinecraftServer.java
:457) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
        at net.minecraft.server.v1_7_R1.ThreadServerApplication.run(SourceFile:6
17) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
Caused by: java.lang.NullPointerException
>