Answer by Ionuț G. Stan for JavaScript global event mechanism

Does this help you:

<script>window.onerror = function() {    alert("Error caught");};xxx();</script>

I'm not sure how it handles Flash errors though...

Update: it doesn't work in Opera, but I'm hacking Dragonfly right now to see what it gets. Suggestion about hacking Dragonfly came from this question:

Mimic Window. onerror in Opera using javascript