Specifically the tool.

I had a NPE with this yesterday. Im pretty sure this is it but I could be wrong. Command was /hawk tool

ava.lang.NullPointerException
at net.minecraft.server.ItemStack.a(ItemStack.java:199)
at net.minecraft.server.InventoryPlayer.f(InventoryPlayer.java:120)
at net.minecraft.server.EntityHuman.v(EntityHuman.java:183)
at net.minecraft.server.EntityPlayer.v(EntityPlayer.java:281)
at net.minecraft.server.EntityLiving.m_(EntityLiving.java:218)
at net.minecraft.server.EntityHuman.m_(EntityHuman.java:97)
at net.minecraft.server.EntityPlayer.a(EntityPlayer.java:193)
at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:299)
at net.minecraft.server.Packet10Flying.a(SourceFile:126)
at net.minecraft.server.NetworkManager.b(NetworkManager.java:226)
at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:89)
at net.minecraft.server.NetworkListenThread.a(SourceFile:105)
at net.minecraft.server.MinecraftServer.h(MinecraftServer.java:454)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:363)
at net.minecraft.server.ThreadServerApplication.run(SourceFile:422)

Is that all there is in the stacktrace? I guess it gives me a bit of an idea (something to do with ItemStack)

Yea that was it, I had it happen twice, almost back to back. It may have crashed my client but Im pretty foggy about that.

I meant to report it last night while it was fresh, I forgot... Was reminded after doing 1st rollback like 20 minutes ago.

Fixed