su-posts Broken Thumbnail

Running WP version 4.9.6
PHP 7.1.4
Using a Child-theme of Twentyseventeen

Best I can guess is that not all my posts have a thumbnail but the su-posts
loop is still trying to access non-existent thumbnails.
<?php if ( has_post_thumbnail() ) : ?>

If you open the link you’ll see the issue.

• This topic was modified 8 years ago by mbd06b.

The page I need help with: [log in to see the link]