[Forwardport] add error message in else condition

[vaibhavahalpara]

Original Pull Request

#17982

Description

STORES > Settings > Configuration > Sales > Shipping Methods > Free Shipping > Enabled > select Yes > > Minimum Order Amount > Enter 50 > Show Method if Not Applicable > Select Yes > Save Config

By configuring above settings Free shipping method should show in frontend with the error message if it is not applicable.

But the shipping is only displayed when it is applicable no matter what the option "Show Method if Not Applicable" value is set to.

Fixed Issues (if relevant)

1. Show Method if Not Applicable for Free Shipping doesn't work. #17977: Show Method if Not Applicable for Free Shipping doesn't work.

Manual testing scenarios

1. Show Method if Not Applicable > Select Yes in this case if free shipping not applied then it should show error message
2. Show Method if Not Applicable > Select No in this case if free shipping not applied then it shouldn't show free shipping method

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 @vaibhavahalpara. Thank you for your contribution.
We will aim to release these changes as part of 2.3.1.
Please check the release notes for final confirmation.