Plugin causing error messages

I am getting the following message on some of my post pages and Rankmath is telling me that the Publishpress Authors plugin is what is causing the issues. Any ideas on a fix?

Warning: Undefined array key “@type” in /home/customer/www/rvtravellife.com/public_html/wp-content/plugins/seo-by-rank-math/includes/modules/schema/class-frontend.php on line 107

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