Description: Unexpected error

java.lang.NullPointerException: Unexpected error
        at net.minecraft.client.network.NetHandlerPlayClient.func_147247_a(NetHandlerPlayClient.java:1552)
        at net.minecraft.network.play.server.S3EPacketTeams.func_148833_a(SourceFile:100)
        at net.minecraft.network.play.server.S3EPacketTeams.func_148833_a(SourceFile:12)
        at net.minecraft.network.NetworkManager.func_74428_b(NetworkManager.java:212)
        at net.minecraft.client.multiplayer.PlayerControllerMP.func_78765_e(PlayerControllerMP.java:273)
        at net.minecraft.client.Minecraft.func_71407_l(Minecraft.java:1602)
        at net.minecraft.client.Minecraft.func_71411_J(Minecraft.java:973)
        at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:898)
        at net.minecraft.client.main.Main.main(SourceFile:148)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)
        at net.minecraft.launchwrapper.Launch.main(Launch.java:28)