Undefined array key “wpb_missed_scheduled_posts_publisher_nonce”

PHP Warning: Undefined array key "wpb_missed_scheduled_posts_publisher_nonce" in /wp-content/plugins/missed-scheduled-posts-publisher/inc/namespace.php on line 181

To correct the warning, the array key “wpb_missed_scheduled_posts_publisher_nonce” should be defined before attempting to access it. You can do this by adding a check to see if the key is set using the isset() function, like this:

Original:

if ( ! verify_no_priv_nonce( $_POST[ ACTION . '_nonce' ] ) ) { wp_send_json_success(); }

Corrected:

if ( isset( $_POST[ ACTION . '_nonce' ] ) && ! verify_no_priv_nonce( $_POST[ ACTION . '_nonce' ] ) ) { wp_send_json_success(); }