JQuery 2.1.3
Firefox 36.0.4

On the initial 'find' and reference to the XMLDocument object, a soft error "not well-formed" in FireFox is thrown, captured and released with continuing execution. Soft error is not thrown for JQuery 2.1.0

not well-formed :1:77

On Fiddle.Net site:
not well-formed :1:79

Open in Firefox, F12, monitor for javascript errors.
http://jsfiddle.net/spknpd92/

Javascript:
var xmlxmlTxt = '<?xml version="1.0"?><general><temperature><myTemp val = "10">The temp is 10</myTemp></temperature></general>';

alert($($.parseXML(xmlxmlTxt)).find('myTemp').attr('val'))