Hello world!

Uncaught Error: wp_get_attachment_picture(): Argument #1 ($attachment_id) must be of type int, null given, called in /var/www/vhosts/devign.site/mcmanus.devign.site/site/themes/devignstudios/template-parts/post-single/header.php on line 37
in /var/www/vhosts/devign.site/mcmanus.devign.site/site/themes/devignstudios/app/wp_media_library.php on line 168

Call stack:

1. wp_get_attachment_picture()
   site/themes/devignstudios/template-parts/post-single/header.php:37
2. require('/var/www/vhosts/devi...st-single/header.php')
   wp-includes/template.php:812
3. load_template()
   wp-includes/template.php:745
4. locate_template()
   wp-includes/general-template.php:206
5. get_template_part()
   site/themes/devignstudios/single.php:8
6. include('/var/www/vhosts/devi...gnstudios/single.php')
   wp-includes/template-loader.php:106
7. require_once('/var/www/vhosts/devi.../template-loader.php')
   wp-blog-header.php:19
8. require('/var/www/vhosts/devi...e/wp-blog-header.php')
   index.php:17