Fatal error: Uncaught Error: call_user_func_array(): Argument #1 ($callback) must be a valid callback, function "show_map" not found or invalid function name
in /home/ycat4254/vakantieuitzoeken.com/www/wp-includes/class-wp-hook.php on line 324

Call stack:

1. WP_Hook::apply_filters()
   wp-includes/class-wp-hook.php:348
2. WP_Hook::do_action()
   wp-includes/plugin.php:517
3. do_action()
   wp-content/plugins/woocommerce/templates/single-product/add-to-cart/external.php:23
4. include()
   wp-content/plugins/woocommerce/includes/wc-core-functions.php:345
5. wc_get_template()
   wp-content/plugins/woocommerce/includes/wc-template-functions.php:1790
6. woocommerce_external_add_to_cart()
   wp-includes/class-wp-hook.php:324
7. WP_Hook::apply_filters()
   wp-includes/class-wp-hook.php:348
8. WP_Hook::do_action()
   wp-includes/plugin.php:517
9. do_action()
   wp-content/plugins/woocommerce/includes/wc-template-functions.php:1719
10. woocommerce_template_single_add_to_cart()
    wp-includes/class-wp-hook.php:324
11. WP_Hook::apply_filters()
    wp-includes/class-wp-hook.php:348
12. WP_Hook::do_action()
    wp-includes/plugin.php:517
13. do_action()
    wp-content/plugins/woocommerce/templates/content-single-product.php:60
14. require()
    wp-includes/template.php:812
15. load_template()
    wp-content/plugins/woocommerce/includes/wc-core-functions.php:284
16. wc_get_template_part()
    wp-content/plugins/woocommerce/templates/single-product.php:37
17. include()
    wp-includes/template-loader.php:106
18. require_once()
    wp-blog-header.php:19
19. require()
    index.php:17