Fatal error: Uncaught TypeError: Return value of NF_Admin_Metaboxes_Calculations::registerReactMetabox() must be an instance of void, none returned in /home/klient.dhosting.pl/alpha/newweb.dkonto.pl/public_html/wp-content/plugins/ninja-forms/includes/Admin/Metaboxes/Calculations.php:37 Stack trace: #0 /home/klient.dhosting.pl/alpha/newweb.dkonto.pl/public_html/wp-content/plugins/ninja-forms/includes/Admin/Metaboxes/Calculations.php(7): NF_Admin_Metaboxes_Calculations->registerReactMetabox() #1 /home/klient.dhosting.pl/alpha/newweb.dkonto.pl/public_html/wp-content/plugins/ninja-forms/ninja-forms.php(367): NF_Admin_Metaboxes_Calculations->__construct() #2 /home/klient.dhosting.pl/alpha/newweb.dkonto.pl/public_html/wp-content/plugins/ninja-forms/ninja-forms.php(1152): Ninja_Forms::instance() #3 /home/klient.dhosting.pl/alpha/newweb.dkonto.pl/public_html/wp-content/plugins/ninja-forms/ninja-forms.php(1155): Ninja_Forms() #4 /home/klient.dhosting.pl/alpha/newweb.dkonto.pl/public_html/wp-settings.php(517): include_once('/home/k in /home/klient.dhosting.pl/alpha/newweb.dkonto.pl/public_html/wp-content/plugins/ninja-forms/includes/Admin/Metaboxes/Calculations.php on line 37