Fatal error: Uncaught TypeError: Return value of NF_Admin_Metaboxes_Calculations::registerReactMetabox() must be an instance of void, none returned in /www/htdocs/w0093f38/simon/blog/wp-content/plugins/ninja-forms/includes/Admin/Metaboxes/Calculations.php:37 Stack trace: #0 /www/htdocs/w0093f38/simon/blog/wp-content/plugins/ninja-forms/includes/Admin/Metaboxes/Calculations.php(7): NF_Admin_Metaboxes_Calculations->registerReactMetabox() #1 /www/htdocs/w0093f38/simon/blog/wp-content/plugins/ninja-forms/ninja-forms.php(367): NF_Admin_Metaboxes_Calculations->__construct() #2 /www/htdocs/w0093f38/simon/blog/wp-content/plugins/ninja-forms/ninja-forms.php(1152): Ninja_Forms::instance() #3 /www/htdocs/w0093f38/simon/blog/wp-content/plugins/ninja-forms/ninja-forms.php(1155): Ninja_Forms() #4 /www/htdocs/w0093f38/simon/blog/wp-settings.php(473): include_once('/www/htdocs/w00...') #5 /www/htdocs/w0093f38/simon/blog/wp-config.php(28): require_once('/www/htdocs/w00...') #6 /www/htdocs/w0093f38/simon/blog/wp-load.php(50): require_once( in /www/htdocs/w0093f38/simon/blog/wp-content/plugins/ninja-forms/includes/Admin/Metaboxes/Calculations.php on line 37