Fatal error: Uncaught Error: Undefined constant "is_product" in /var/www/web63/html/herzblut/wp-content/themes/HERZBLUT/functions.php:282 Stack trace: #0 /var/www/web63/html/herzblut/wp-includes/class-wp-hook.php(287): variable_products_name('') #1 /var/www/web63/html/herzblut/wp-includes/class-wp-hook.php(311): WP_Hook->apply_filters(NULL, Array) #2 /var/www/web63/html/herzblut/wp-includes/plugin.php(484): WP_Hook->do_action(Array) #3 /var/www/web63/html/herzblut/wp-includes/general-template.php(3005): do_action('wp_head') #4 /var/www/web63/html/herzblut/wp-content/themes/HERZBLUT/header.php(22): wp_head() #5 /var/www/web63/html/herzblut/wp-includes/template.php(730): require_once('/var/www/web63/...') #6 /var/www/web63/html/herzblut/wp-includes/template.php(676): load_template('/var/www/web63/...', true, Array) #7 /var/www/web63/html/herzblut/wp-includes/general-template.php(48): locate_template(Array, true, true, Array) #8 /var/www/web63/html/herzblut/wp-content/plugins/woocommerce/templates/archive-product.php(20): get_header('shop') #9 /var/www/web63/html/herzblut/wp-content/plugins/woocommerce/includes/wc-core-functions.php(345): include('/var/www/web63/...') #10 /var/www/web63/html/herzblut/wp-content/plugins/woocommerce/templates/taxonomy-product-tag.php(22): wc_get_template('archive-product...') #11 /var/www/web63/html/herzblut/wp-includes/template-loader.php(106): include('/var/www/web63/...') #12 /var/www/web63/html/herzblut/wp-blog-header.php(19): require_once('/var/www/web63/...') #13 /var/www/web63/html/herzblut/index.php(17): require('/var/www/web63/...') #14 {main} thrown in /var/www/web63/html/herzblut/wp-content/themes/HERZBLUT/functions.php on line 282