CMS Made Simple Forums

I've edited my {content_image} function to display an tag instead of an tag if the extension of the file isn't an image (jpg, gif, etc). The only issue I'm running into is that I get the "Error Retrieving File List" message when trying to pull in a directory from the File Manager that doesn't contain images.

Does anyone know which page pulls in the File List for {content_image} tags when adding or editing a page? Thanks a bunch for any assistance!