Warning: Undefined variable $block in /var/www/magento/html/app/design/frontend/bbnt/base/Magento_Sales/templates/order/invoice/download.phtml on line 2

Fatal error: Uncaught Error: Call to a member function getOrder() on null in /var/www/magento/html/app/design/frontend/bbnt/base/Magento_Sales/templates/order/invoice/download.phtml:2 Stack trace: #0 {main} thrown in /var/www/magento/html/app/design/frontend/bbnt/base/Magento_Sales/templates/order/invoice/download.phtml on line 2