Error when using short url

When using a short url for the youtube link the script crashes. Full url is fine.

Warning: file_get_contents(https://img.youtube.com/vi//maxresdefault.jpg): failed to open stream: HTTP request failed! HTTP/1.0 404 Not Found in /home/andrewc/public_html/ghostinc/blog/wp-content/plugins/youtube-thumbnail-to-featured-image/featured-youtube-thumbnail.php on line 83

Warning: Cannot modify header information – headers already sent by (output started at /home/andrewc/public_html/ghostinc/blog/wp-content/plugins/youtube-thumbnail-to-featured-image/featured-youtube-thumbnail.php:83) in /home/andrewc/public_html/ghostinc/blog/wp-admin/post.php on line 235

Warning: Cannot modify header information – headers already sent by (output started at /home/andrewc/public_html/ghostinc/blog/wp-content/plugins/youtube-thumbnail-to-featured-image/featured-youtube-thumbnail.php:83) in /home/andrewc/public_html/ghostinc/blog/wp-includes/pluggable.php on line 1196

https://www.ads-software.com/plugins/youtube-thumbnail-to-featured-image/