Fatal error: Uncaught TypeError: call_user_func_array(): Argument #1 ($callback) must be a valid callback, function "sub_nav_walker" not found or invalid function name in /homepages/44/d30956500/htdocs/delang.de/wp-includes/class-wp-hook.php:308 Stack trace: #0 /homepages/44/d30956500/htdocs/delang.de/wp-includes/plugin.php(205): WP_Hook->apply_filters('karma_walker', Array) #1 /homepages/44/d30956500/htdocs/delang.de/wp-content/themes/karma/framework/karma-megamenu.php(35): apply_filters('karma_mega_menu...', 'karma_walker') #2 /homepages/44/d30956500/htdocs/delang.de/wp-includes/class-wp-hook.php(308): karma_megamenu->modify_arguments(Array) #3 /homepages/44/d30956500/htdocs/delang.de/wp-includes/plugin.php(205): WP_Hook->apply_filters(Array, Array) #4 /homepages/44/d30956500/htdocs/delang.de/wp-includes/nav-menu-template.php(97): apply_filters('wp_nav_menu_arg...', Array) #5 /homepages/44/d30956500/htdocs/delang.de/wp-content/themes/karma/theme-template-part-horizontal-sub-menu.php(38): wp_nav_menu(Array) #6 /homepages/44/d30956500/htdocs/delang.de/wp-includes/template.php(785): require('/homepages/44/d...') #7 /homepages/44/d30956500/htdocs/delang.de/wp-includes/template.php(718): load_template('/homepages/44/d...', false, Array) #8 /homepages/44/d30956500/htdocs/delang.de/wp-includes/general-template.php(204): locate_template(Array, true, false, Array) #9 /homepages/44/d30956500/htdocs/delang.de/wp-content/themes/karma/template-full-width.php(10): get_template_part('theme-template-...') #10 /homepages/44/d30956500/htdocs/delang.de/wp-includes/template-loader.php(106): include('/homepages/44/d...') #11 /homepages/44/d30956500/htdocs/delang.de/wp-blog-header.php(19): require_once('/homepages/44/d...') #12 /homepages/44/d30956500/htdocs/delang.de/index.php(17): require('/homepages/44/d...') #13 {main} thrown in /homepages/44/d30956500/htdocs/delang.de/wp-includes/class-wp-hook.php on line 308
