If you forget to initialise a variable which you thought was a Dictionary - you get a confusing error message: "Error: only integers should be used as indices” if you try an at:put:
This is a consequence of having at:put: defined on Object (which is a bit nasty) Should UndefinedObject at least override this and signal something a bit more obvious? This is a common and easily done thing and we don't support it very well. I just did it in some code, and was scratching my head initially until I read the stack properly and realised it was something much simpler than I thought I had done. Any thoughts on this?