I'm not sure what kind of luck you'll have with repro, since I have a kind of specific environment set up (selenium) for using it with, but you're welcome to try.
The code for the workhorse is here (for the next month):
http://pastebin.com/PNZ4adnZThe rest of the xpi is here (until it's no longer needed):
https://www.box.com/s/43b2881a1a66fd3acd85You will need a page that causes the net panel to populate and also has an element with an id of "hopstats" (as this is the element that will be populated with the net urls).
The following HTML will display an ad (to populate the net panel) and a textarea with the appropriate id.
http://pastebin.com/Eu9SeDy6Furthermore, you will need to have firebug open and opened to the net panel.
Ideally, the textarea should be populated with the urls from the net panel on page load.
In my selenium environment, the extension runs fine on first load, but after about 18 page reloads, it calls it quits altogether.
When I try in a normal firefox instance, it seems like the onLoad part doesn't trigger. It also adds a "Url Quality" button to the net panel to manually trigger it.
On further investigation, I realized that in the selenium environment, the manual button still works, so it looks like it's just the "on page load" part that's breaking.
Two things to note:
1) I have upgraded to firebug 1.10b3 and the problem persists
2) This definitely seems error related, and not just me using onLoad wrong (although I may be doing that as well), because when I replace line 58 with something obviously erroneous, like:
populate,Quality(,?: f,uncti,on(,anel,, tar,et) {,},{}{}}}
I still don't see any errors.