How to catch a SharePoint "Error: Access Denied" page

[ChetUbetcha]

I have a document viewer that displays inline pdfs. Problem is, some people don't have access to certain documents due to restricted access on the SharePoint server. How do I catch the "Error: Access Denied" result when they don['t have access so I can display a message that they don't have permission to view the page? The page locks up once they hit the blocked SharePoint page.

Thanks!