<script>
		(function(){
		var old = window.onerror;
		window.onerror = function (msg, url, line) {
			if(typeof old==="function") { old(msg,url,line);} 
			_gaq.push(['_trackEvent', 'Error Log', msg, url+'_'+line]);
		};
		}());
		</script>
		<script type="text/javascript"> 

		  var _gaq = _gaq || [];
		  _gaq.push(['_setAccount', 'UA-XXXXXXXXX-Y']);
		  _gaq.push(['_trackPageview']);

		  (function() {
		    var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
		    ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
		    var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
		  })();

		</script>

http://dl.dropbox.com/u/397675/error_test.html

1. no need to wrap the (potentially) offending code in try/catch
2. use window.onerror:

Debugging JS with GA by Yahel Carmon

JavaScript