I added the following code to lines 108 and 157
if(function_exists('has_post_thumbnail') && has_post_thumbnail($rdcsc_posts->ID))
$rdscf_output.='<div class=csc_post_thumbnail>' . get_the_post_thumbnail($rdcsc_posts->ID, 'thumbnail') . '</div>';
This seems to get around the problem by only displaying thumbnails if the theme supports it.
