Better error message when "0compile gui" gets the wrong number of arguments
Better error message when "0compile gui" gets the wrong number of arguments

Was displaying an empty error box.

dabrahams/0compile,timbertson/0compile,gfxmonk/0compile,0install/0compile,gfxmonk/0compile,timbertson/0compile,0install/0compile,0install/0compile,dabrahams/0compile