calling store.UpdateFeed and store.UpdateFeedError in a defer function

[shizunge]

To calculate and to commit next check at in a single place.

Want to do this cleanup before working on #412

Do you follow the guidelines?

• I have tested my changes: Deployed and tested with my own feeds. Run with 300+ feeds, intentionally including feeds with errors.
• I read this document: https://miniflux.app/faq.html#pull-request

[shizunge]

It seems unable to make it depend on my branch or another PR.

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/proposing-changes-to-your-work-with-pull-requests/changing-the-base-branch-of-a-pull-request

[shizunge]

rebased