warning “Attempt to read property…”

Hello,
I am using the [su_posts] shortcode for the home page of my blog.
Everything works fine, except that each time you visit this page, warnings appear in the error_log file:
“Attempt to read property” ID “on bool (or on string, or on int, or on array, or on float …) in /wp-includes/post-thumbnail-template.php on line 106”
I’ve done a lot of checking and it’s [su_posts] that generates these warnings.
I also specify that I created a default-loop.php template in the folders of my child theme; but the problem remains if I delete it (and therefore use the plugin template)
I am using the latest version of wordpress as well as ultimate shortcode.
Thanks for your help.
Regards,
Gilles

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