Plugin throwing errors into my WP

Across the top of my admin pages, I have this all the time. What is the problem here:

Warning: Trying to access array offset on value of type bool in /homepages/7/d423752994/htdocs/DuluthHistory/wp-content/plugins/codecanyon-8vEeZ32V-post-timeline-wordpress-plugin/includes/option-tree/includes/class-ot-settings.php on line 395

Warning: Trying to access array offset on value of type bool in /homepages/7/d423752994/htdocs/DuluthHistory/wp-content/plugins/codecanyon-8vEeZ32V-post-timeline-wordpress-plugin/includes/option-tree/includes/class-ot-settings.php on line 396

Warning: Cannot modify header information - headers already sent by (output started at /homepages/7/d423752994/htdocs/DuluthHistory/wp-content/plugins/codecanyon-8vEeZ32V-post-timeline-wordpress-plugin/includes/option-tree/includes/class-ot-settings.php:395) in /homepages/7/d423752994/htdocs/DuluthHistory/wp-admin/includes/misc.php on line 1381

Warning: Cannot modify header information - headers already sent by (output started at /homepages/7/d423752994/htdocs/DuluthHistory/wp-content/plugins/codecanyon-8vEeZ32V-post-timeline-wordpress-plugin/includes/option-tree/includes/class-ot-settings.php:395) in /homepages/7/d423752994/htdocs/DuluthHistory/wp-includes/functions.php on line 6880

Warning: Cannot modify header information - headers already sent by (output started at /homepages/7/d423752994/htdocs/DuluthHistory/wp-content/plugins/codecanyon-8vEeZ32V-post-timeline-wordpress-plugin/includes/option-tree/includes/class-ot-settings.php:395) in /homepages/7/d423752994/htdocs/DuluthHistory/wp-includes/pluggable.php on line 1416

Warning: Cannot modify header information - headers already sent by (output started at /homepages/7/d423752994/htdocs/DuluthHistory/wp-content/plugins/codecanyon-8vEeZ32V-post-timeline-wordpress-plugin/includes/option-tree/includes/class-ot-settings.php:395) in /homepages/7/d423752994/htdocs/DuluthHistory/wp-includes/pluggable.php on line 1419

Warning: Cannot modify header information - headers already sent by (output started at /homepages/7/d423752994/htdocs/DuluthHistory/wp-content/plugins/codecanyon-8vEeZ32V-post-timeline-wordpress-plugin/includes/option-tree/includes/class-ot-settings.php:395) in /homepages/7/d423752994/htdocs/DuluthHistory/wp-includes/pluggable.php on line 1416

Warning: Cannot modify header information - headers already sent by (output started at /homepages/7/d423752994/htdocs/DuluthHistory/wp-content/plugins/codecanyon-8vEeZ32V-post-timeline-wordpress-plugin/includes/option-tree/includes/class-ot-settings.php:395) in /homepages/7/d423752994/htdocs/DuluthHistory/wp-includes/pluggable.php on line 1419