Inherited a theme I didn't create and trying to add nested comments

I inherited a website and have been trying to add nested comments to the custom theme. I tried following a tutorial I found online, but it broke the site when I tried them out. I’m copying my comments.pp code here in case anyone can point me in the direction of a good solution.

I tried following the instructions here https://www.problogdesign.com/wordpress/advanced-wordpress-comment-styles-and-tricks/ which broke the site. I then tried downloading the completed theme from the site and added the authors functions to my functions.php as well as his comment CSS to my stylesheet and replaced my comments.php file with his comments file. It initially looks like it works, but then I get the following error whenever I click “reply”

Warning: Cannot modify header information – headers already sent by (output started at /home/content/m/o/r/morbidgames/html/bmgtest/wp-content/themes/bimodal_theme/functions.php:41) in /home/content/m/o/r/morbidgames/html/bmgtest/wp-includes/comment.php on line 586

Warning: Cannot modify header information – headers already sent by (output started at /home/content/html/bmgtest/wp-content/themes/bimodal_theme/functions.php:41) in /home/content/html/bmgtest/wp-includes/comment.php on line 587

Warning: Cannot modify header information – headers already sent by (output started at /home/content/html/bmgtest/wp-content/themes/bimodal_theme/functions.php:41) in /home/content/html/bmgtest/wp-includes/comment.php on line 588

Warning: Cannot modify header information – headers already sent by (output started at /home/content/html/bmgtest/wp-content/themes/bimodal_theme/functions.php:41) in /home/content/html/bmgtest/wp-includes/pluggable.php on line 881