Warnings and other difficulities after updating the extension to v2.3.0 or above in magento

As a part of v2.3.0 update, extension structure undergone serious changes.

As a result, if an update from older version to v2.3.0 or above will be performed 'as is' without using Composer, some loose files will persist in extension folder.

The extension may misbehave or cease to work because of these redundant files.

To resolve it:

• without using Composer: please remove the content of [Magento root folder]/app/code/Amasty/Feed prior to uploading the package with updated version.
• with Composer: no additional actions required.

Composer will clean [Magento root folder]/vendor/amasty/feed automatically before installing the update, effectively, removing the difficulity's cause automatically.

Reference for Composer usage is available here.