REQUIRED: get_bloginfo(‘template_url’) was found in the file search.php. Use get_template_directory_uri() instead

Is the image in a child theme? If so, use get_stylesheet_directory_uri() instead as it will grab the child theme URL. get_template_directory_uri() grabs the parent theme.

Depending on your PHP version adding a semicolon also might make a difference, and typically image src uses double quotes rather than single.

<img src="https://wordpress.stackexchange.com/questions/286570/<?php echo get_stylesheet_directory_uri(); ?>/img/no_results_found.png" />