[Plugin: Auto Featured Image] Problem

I install the plugin but not work, and this error appear before the first post thumbnail, and now i can put any fetured images in the theme.

anyway to fix? thanks.

Catchable fatal error: Object of class WP_Error could not be converted to string in /home5/casadep2/public_html/wp-content/themes/parallelus-mingle3/framework/utilities/media-functions.php on line 152

Warning: missing endblock() for startblock(‘middle’) in /home5/casadep2/public_html/wp-content/themes/parallelus-mingle3/framework/theme-functions/layout-and-design.php on line 137

https://www.ads-software.com/extend/plugins/auto-featured-image/