Wrap Errorception to provide stack traces in some browsers

errorception.js

window.onerror = (function(old) {

    return function() {

        var args = [].slice.call(arguments);

        for (var i = 0, l = arguments.length; i < l; i++) {
            if (args[i] instanceof Error) {
                window._errs.push(args[i]);
            }
        }

        return old.apply(this, arguments);
    }

})(window.onerror);