In survival mode I made a random guess at what I thought was the Item ID of what I was looking for, typed in /give username 175 64 15, and then watched the screen go black and quickly close.

The error message says-
"Failed to get item icon - We're sorry, but it seems that there was an while rendering an item. If you gave yourself an invalid item or inputted an invalid superflat biome ID, please revert these actions. If you were trying to connect to a server, please let the server owners know of this error. Please report how you produced this error to http://bugs.mojang.com/!"

I now cannot get past "loading terrain" without the same crash and error message. I did a little looking around but didn't see how to possibly revert the action of giving myself an invalid item.

Sorry if this has been solved already, just looking for a little advice!