I get this error: Fatal error: Uncaught Error: Call to a member function using_index_permalinks() on null in /home/customer/www/foodstories.com.cy/public_html/wp-includes/rest-api.php:403 Stack trace: #0 /home/customer/www/foodstories.com.cy/public_html/wp-content/plugins/sg-cachepress/core/Supercacher/Supercacher.php(175): get_rest_url() #1 /home/customer/www/foodstories.com.cy/public_html/wp-content/plugins/sg-cachepress/core/Supercacher/Supercacher_Posts.php(31): SiteGround_Optimizer\Supercacher\Supercacher->purge_rest_cache() #2 /home/customer/www/foodstories.com.cy/public_html/wp-content/plugins/sg-cachepress/core/Supercacher/Supercacher_Posts.php(156): SiteGround_Optimizer\Supercacher\Supercacher_Posts->purge_post_cache(1884) #3 /home/customer/www/foodstories.com.cy/public_html/wp-includes/class-wp-hook.php(294): SiteGround_Optimizer\Supercacher\Supercacher_Posts->purge_all_post_cache(1884) #4 /home/customer/www/foodstories.com.cy/public_html/wp-includes/class-wp-hook.php(316): WP_Hook->apply_filters(1884, Array) #5 /home/customer/ww in /home/customer/www/foodstories.com.cy/public_html/wp-includes/rest-api.php on line 403