19:15:15 [SEVERE] Could not pass event InventoryClickEvent to FTBHelper v1.5
org.bukkit.event.EventException
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:437)
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62)
        at org.bukkit.plugin.TimedRegisteredListener.callEvent(TimedRegisteredListener.java:31)
        at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:479)
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:464)
        at net.minecraft.network.NetServerHandler.func_72523_a(NetServerHandler.java:2088)
        at net.minecraft.network.packet.Packet102WindowClick.func_73279_a(Packet102WindowClick.java:46)
        at net.minecraft.network.TcpConnection.func_74428_b(TcpConnection.java:470)
        at net.minecraft.network.NetServerHandler.func_72570_d(NetServerHandler.java:233)
        at net.minecraft.network.NetworkListenThread.func_71747_b(NetworkListenThread.java:54)
        at net.minecraft.server.dedicated.DedicatedServerListenThread.func_71747_b(DedicatedServerListenThread.java:34)
        at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:910)
        at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:330)
        at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:777)
        at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:659)
        at net.minecraft.server.ThreadMinecraftServer.run(ThreadMinecraftServer.java:16)
Caused by: java.lang.StringIndexOutOfBoundsException: String index out of range: -1
        at java.lang.String.substring(Unknown Source)
        at FTBRestrict.InventoryListener.onInventoryClick(InventoryListener.java:34)
        at sun.reflect.GeneratedMethodAccessor66.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:435)
        ... 15 more