Merge forwardport of #12091 to 2.3-develop branch

Applied pull request patch https://github.com/magento/magento2/pull/12091.patch (created by @lazyguru) based on commit(s):
  1. 48a0415

Author: magento-engcom-team

app/code/Magento/Shipping/Controller/Adminhtml/Order/Shipment/Save.php

@@ -108,6 +108,7 @@ public function execute()
         }
 
         $isNeedCreateLabel = isset($data['create_shipping_label']) && $data['create_shipping_label'];
+        $responseAjax = new \Magento\Framework\DataObject();
 
         try {
             $this->shipmentLoader->setOrderId($this->getRequest()->getParam('order_id'));
@@ -143,7 +144,6 @@ public function execute()
             $shipment->register();
 
             $shipment->getOrder()->setCustomerNoteNotify(!empty($data['send_email']));
-            $responseAjax = new \Magento\Framework\DataObject();
 
             if ($isNeedCreateLabel) {
                 $this->labelGenerator->create($shipment, $this->_request);