Fatal error: Uncaught TypeError: call_user_func_array(): Argument #1 ($callback) must be a valid callback, non-static method simple_breaks::add_button() cannot be called statically in /home/trentmka/public_html/teaching/wp-includes/class-wp-hook.php:288 Stack trace: #0 /home/trentmka/public_html/teaching/wp-includes/class-wp-hook.php(312): WP_Hook->apply_filters(Object(RegenerateThumbnails), Array) #1 /home/trentmka/public_html/teaching/wp-includes/plugin.php(478): WP_Hook->do_action(Array) #2 /home/trentmka/public_html/teaching/wp-settings.php(523): do_action('init') #3 /home/trentmka/public_html/teaching/wp-config.php(90): require_once('/home/trentmka/...') #4 /home/trentmka/public_html/teaching/wp-load.php(37): require_once('/home/trentmka/...') #5 /home/trentmka/public_html/teaching/wp-blog-header.php(13): require_once('/home/trentmka/...') #6 /home/trentmka/public_html/teaching/index.php(17): require('/home/trentmka/...') #7 {main} thrown in /home/trentmka/public_html/teaching/wp-includes/class-wp-hook.php on line 288