Debug: Undefined constant WP_Admin

This plugin works well for me.

I wanted to point out one error message that appears throughout the site for all users while debug is on in WP-Config:

Notice: Use of undefined constant WP_ADMIN – assumed ‘WP_ADMIN’ in / wp-content/plugins/replace-featured-image-with-video/pt-page-featured-video.php on line 12

https://ww.wp.xz.cn/plugins/replace-featured-image-with-video/