I’ve just today upgraded my sites to PHP 7.2 and I’ve started seeing a PHP warning for wp-show-posts.
The error is [29-May-2018 06:05:16 UTC] PHP Warning: count(): Parameter must be an array or an object that implements Countable in …(truncated)/wp-content/plugins/wp-show-posts/admin/ajax.php on line 38.
I think it might be a compatibility issue with 7.2 as I haven’t seen this warning before? I’ve been running 7.0 up until this week. I noticed another WP plugin (not one of your’s) had the same warning a few months back over at WP.org.