Wordpress Pages Show Missing Photos Error

When I look at myWordpress website, there is this error message on every page, even the pages that don’t have any images
There are no photos with those IDs or post does not have any attached images!
I am using the Sinatra theme but I had the same problem when I was using the Twenty Nineteen theme. I am also using the Justified Image Grid plug-in and the error seems to be coming from this plug-in.

To solve this problem, I went to the plug-ins directory and downloaded justified-image-grid-core.php and removed the error message manually there. That did the trick.