Fatal error: Uncaught TypeError: Return value of NF_Admin_Metaboxes_Calculations::registerReactMetabox() must be an instance of void, none returned in /data/web/virtuals/148462/virtual/www/domains/trewald.cz/wp-content/plugins/ninja-forms/includes/Admin/Metaboxes/Calculations.php:37 Stack trace: #0 /data/web/virtuals/148462/virtual/www/domains/trewald.cz/wp-content/plugins/ninja-forms/includes/Admin/Metaboxes/Calculations.php(7): NF_Admin_Metaboxes_Calculations->registerReactMetabox() #1 /data/web/virtuals/148462/virtual/www/domains/trewald.cz/wp-content/plugins/ninja-forms/ninja-forms.php(367): NF_Admin_Metaboxes_Calculations->__construct() #2 /data/web/virtuals/148462/virtual/www/domains/trewald.cz/wp-content/plugins/ninja-forms/ninja-forms.php(1152): Ninja_Forms::instance() #3 /data/web/virtuals/148462/virtual/www/domains/trewald.cz/wp-content/plugins/ninja-forms/ninja-forms.php(1155): Ninja_Forms() #4 /data/web/virtuals/148462/virtual/www/domains/trewald.cz/wp-settings.php(418): include_once('/data/web/virtu...') #5 / in /data/web/virtuals/148462/virtual/www/domains/trewald.cz/wp-content/plugins/ninja-forms/includes/Admin/Metaboxes/Calculations.php on line 37