Seems like an overlooked bug. I have addressed this issue with the admins, and should be fixed soon.

arrow shape wizard bug
'newLay' is null or not an object - when 2nd layer exists
Hi, I wanted to make an animated cursor with an arrow tip, and the arrow wizard is very practical for that.
However, to work less destructively, I wanted to place this arrow on a second layer ontop of my image layer.
But the wizard refuses to work when more layers than the default exist. It spits out the error code in the subtitle.
Do I have to modify the layer somehow? Drawing something on it doesn't fix the error.