Error on Install

Warning: Declaration of MJM_Walker_SlugValueCategoryDropdown::start_el(&$output, $category, $depth, $args, $id = 0) should be compatible with Walker_CategoryDropdown::start_el(&$output, $category, $depth = 0, $args = Array, $id = 0) in /home/bserverc/public_html/clinicsoft/wp-content/plugins/mjm-clinic/class-misc.php on line 17

Warning: Cannot modify header information - headers already sent by (output started at /home/bserverc/public_html/clinicsoft/wp-content/plugins/mjm-clinic/class-misc.php:17) in /home/bserverc/public_html/clinicsoft/wp-admin/includes/misc.php on line 1116

Warning: Cannot modify header information - headers already sent by (output started at /home/bserverc/public_html/clinicsoft/wp-content/plugins/mjm-clinic/class-misc.php:17) in /home/bserverc/public_html/clinicsoft/wp-includes/option.php on line 919

Warning: Cannot modify header information - headers already sent by (output started at /home/bserverc/public_html/clinicsoft/wp-content/plugins/mjm-clinic/class-misc.php:17) in /home/bserverc/public_html/clinicsoft/wp-includes/option.php on line 920

This is on the latest version of WordPress and a fresh install with no plugin.