Catchable Fatal Error in media library

Hi, First of all great theme thanks.
I have just came across this error when trying to view pdf files from the Media library by selecting the “View” link in the file. The pdf doesn’t open and shows the below error.

Catchable fatal error: Object of class WP_Error could not be converted to string in /home/tigersaa/public_html/wp-content/themes/responsive/includes/functions.php on line 452

The photos in the library open with no problem but there is an error in the widget on the page and other photos appear on the page. View the photo error https://www.tigers.asn.au/?attachment_id=101

I tried opening with the full address and there is no problem.

Thanks