First off I'd love to see errors be able to trace say the last 2-3 commands which called an alias from script:

* error: invalid parameters, /futon (line 7, file.mrc)
* callee: /myFutonCaller (line 8, file.mrc)
* callee: /myFutonCallerCaller (line 9, file.mrc)

etc... it'd be a mini stack trace kinda like java. I don't hold high hopes for that suggestioning going far, but it'd be a useful debutgging tool.

So would this:
hotlinked errors which jump to the error line in the script file - its already possible to do with mIRC's code, as you can jump to lines WITHIN the editor, and I'm sure that the hotlinks could be setup with an 'error' flag whcih does infact open the editor at line X

If we can't have that, perhaps access to displaying the editor and VERY rudimentary control (jump to line, find X in editor, save, etc)