> Is the line number reference a JavaScript line number?
Probably yes, if it is coming from the browser. If you have the
compacted mode on, it is useless, but without you can look at the code
in the browser debugger (F12 in Chrome) and then put a breakpoint and
run the page again. Then you can see the call stack to find out what is
happening, and from that you can see where it is in the EWB code.