This can be achieved by downloading and installing two things (or three if you don’t have the browser Firefox):
1. Download and install the Adobe Flash debug player at http://www.adobe.com/support/flashplayer/downloads.html. This will give you error warnings of all Flash related errors.
2. Download and install the Firefox add-on called Flashtracer at http://www.sephiroth.it/firefox/flashtracer/ and adjust the settings so the debugger errors/traces will appear in the sidebar of your browser.