[Backport] Credit memo email template file: fixing incorrect object type error

[gelanivishal]

Original Pull Request

#16438

Description

When creating a credit memo and checking the "Email" checkbox, you would get an error like:

Fatal error: Uncaught TypeError: Argument 1 passed to Magento\Sales\Block\Order\Email\Items\Order\DefaultOrder::getItemPrice() must be an instance of Magento\Sales\Model\Order\Item, instance of Magento\Sales\Model\Order\Creditmemo\Item given, called in /var/www/sites/magento/vendor/magento/module-sales/view/frontend/templates/email/items/creditmemo/default.phtml on line 34 and defined in /var/www/sites/magento/vendor/magento/module-sales/Block/Order/Email/Items/Order/DefaultOrder.php on line 99

Adding ->getOrderItem() sends the correct type and the error is resolved. Reference.

Manual testing scenarios

1. Create an order
2. Invoice the order
3. Create a credit memo for the order, and check "Send email".
4. You should receive an email with the credit memo instead of an error.

Contribution checklist

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds on Travis CI are green)

[magento-engcom-team]

Hi @ihor-sviziev, thank you for the review.
ENGCOM-2572 has been created to process this Pull Request

[magento-engcom-team]

Hi @gelanivishal. Thank you for your contribution.
We will aim to release these changes as part of 2.1.15.
Please check the release notes for final confirmation.