2.9.91.1 bootstrap/firefox - it beeps to wake the dead

[Adam Worrall <abworrall gmail com>]

I've managed to turn an antique RedHat7.3 OS into a lovely modern
looking thing thanks to Garnome - so thank you all for making the
complexity of Gnome compilation tractable :)

I have a firefoxism that perhaps someone here has come across;
basically, it keeps discovering stacks of JavaScript errors on most
websites, and each time it finds one it makes my PC beep, which is
irritating. This isn't the typeahead problem; it happens all the time,
e.g. when using GMail. And I can see the errors piling up in the JS
console.

The public firefox builds don't do this; is there some build-time or
run-time setting to make the JS engine a bit less excitable ?

Thanks for your time,

 - Adam