I know this one may not be possible or maybe needs to be done at the Firebug level, but for our use with students it would be nice to know on which line the the error occurred when running the multi-line editor.
Great tool and great job,
Found a work around that seems consistent. If there are more than 20 lines Firebug prints the line number of the page, assuming where the code injection took place, which can be subtracted by the place of the injection to get the line number. That will work for now.