java.lang.NullPointerException: Unexpected error
	at net.minecraft.item.ItemBlock.func_180614_a(ItemBlock.java:58)
	at net.minecraft.item.ItemStack.func_179546_a(ItemStack.java:187)
	at net.minecraft.client.multiplayer.PlayerControllerMP.func_187099_a(PlayerControllerMP.java:467)
	at net.minecraft.client.Minecraft.func_147121_ag(Minecraft.java:1579)
	at net.minecraft.client.Minecraft.func_184117_aA(Minecraft.java:2254)
	at net.minecraft.client.Minecraft.func_184118_az(Minecraft.java:2020)
	at net.minecraft.client.Minecraft.func_71407_l(Minecraft.java:1808)
	at net.minecraft.client.Minecraft.func_71411_J(Minecraft.java:1098)
	at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:398)
	at net.minecraft.client.main.Main.main(SourceFile:123)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.lang.reflect.Method.invoke(Unknown Source)
	at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)
	at net.minecraft.launchwrapper.Launch.main(Launch.java:28)


A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

-- Head --
Thread: Client thread
Stacktrace:
	at net.minecraft.item.ItemBlock.func_180614_a(ItemBlock.java:58)
	at net.minecraft.item.ItemStack.func_179546_a(ItemStack.java:187)
	at net.minecraft.client.multiplayer.PlayerControllerMP.func_187099_a(PlayerControllerMP.java:467)
	at net.minecraft.client.Minecraft.func_147121_ag(Minecraft.java:1579)
	at net.minecraft.client.Minecraft.func_184117_aA(Minecraft.java:2254)
	at net.minecraft.client.Minecraft.func_184118_az(Minecraft.java:2020)