Enchanting a Bow : Error

Just 4 Info
Server Error and User Kick from Server :

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Code:

[WARNING] Failed to handle packet: java.lang.NullPointerException
java.lang.NullPointerException
    at net.minecraft.server.ContainerEnchantTable.a(ContainerEnchantTable.java:147)
    at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:1008)
    at net.minecraft.server.Packet108ButtonClick.handle(SourceFile:18)
    at net.minecraft.server.NetworkManager.b(NetworkManager.java:226)
    at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:100)
    at net.minecraft.server.NetworkListenThread.a(NetworkListenThread.java:78)
    at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:536)
    at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:434)
    at net.minecraft.server.ThreadServerApplication.run(SourceFile:465)