Fatal error: Uncaught TypeError: strtoupper() expects parameter 1 to be string, null given in /home/h261919/domains/instakalla.ir/public_html/wp-content/plugins/wp-rocket/inc/Engine/Optimization/LazyRenderContent/Frontend/Processor/Dom.php:145 Stack trace: #0 /home/h261919/domains/instakalla.ir/public_html/wp-content/plugins/wp-rocket/inc/Engine/Optimization/LazyRenderContent/Frontend/Processor/Dom.php(145): strtoupper(NULL) #1 /home/h261919/domains/instakalla.ir/public_html/wp-content/plugins/wp-rocket/inc/Engine/Optimization/LazyRenderContent/Frontend/Processor/Dom.php(107): WP_Rocket\Engine\Optimization\LazyRenderContent\Frontend\Processor\Dom->add_hash_to_element(Object(DOMElement), 2, ' ...') #2 /home/h261919/domains/instakalla.ir/public_html/wp-content/plugins/wp-rocket/inc/Engine/Optimization/LazyRenderContent/Frontend/Controller.php(155): WP_Rocket\Engine\Optimization\LazyRenderContent\Frontend\Processor\Dom->add_hashes(' ...') #3 /home/h261919/domains/instakalla.ir/public_html/wp-conte in /home/h261919/domains/instakalla.ir/public_html/wp-content/plugins/wp-rocket/inc/Engine/Optimization/LazyRenderContent/Frontend/Processor/Dom.php on line 145