WORLDEDIT-3223 - Reported by Jaegermeister

If you try to use //fillr with a position y < 0
Error:
http://pastebin.com/pB64pq8w

using:
WorldEdit Build #3347 and newest Spigot Build

Comment by wizjany

It is..rather expected to get an error in this case. Although I suppose a better exception could be thrown to warn the user?
I am not sure if we really want to be catching every IllegalArgumentException though.