Hum, wonder if we'll ever see one...
For my part, I'd be more than contented with
extended find- and syntax highlighting options of the scripts editor (had not to match with apps like notepad++ or regexbuddy, just something
light 
) ... I'm unsure whether or not this had been requested before.
With or without such a feature, the best debugging engine will always be the human brain. And in addition, there are all that help chans, boards and tutorials out there
(Just for convenience, some examples of helpful links:
"find the bug" "common pitfalls" "syntax tutorial" "evaluation brackets" "debugging" )
