Debugging a YUI Javascript error

I am working on making a widget that uses a YUI Javascript library to render a hike map, a trailhead and the route. Here is the example of what I am trying to do

http://www.comehike.com/outdoors/widget.php?hike_id=108&height=600&width=700

But if you look at 开发者_开发知识库the JS error console, it is complaining about offsetWidth variable being undefined. I am a bit stuck in how to debug this. Any ideas?

Thanks!

This question answers this question nicely: How to disable YUI2 silent failing?

YAHOO.widget.Logger.enableBrowserConsole();
YAHOO.util.Event.throwErrors = true;