Fix homepage-articles block not parsing nested inner blocks

[kevin940726]

All Submissions:

• Have you followed the Newspack Contributing guideline?
• Does your code follow the WordPress' coding standards and VIP Go coding standards?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changes proposed in this Pull Request:

Related to Automattic/wp-calypso#91839. This will also need a sync to https://github.com/Automattic/jetpack.

The Homepage Posts block (or the Blog Posts block in calypso and jetpack) won't load in the site editor. This is because the block fails to discover itself with getBlocks. This was partially fixed in #1066 but didn't take nested inner blocks into accounts. Since the core/post-content block is similar, this PR recursively calls getBlocks on all nested inner blocks.

How to test the changes in this Pull Request:

Test with wp-now locally:

1. Switch to this branch and run npm install.
2. Run npm start to build the blocks locally.
3. Run npx @wp-now/wp-now start, it should open a webpage.
4. Go to Pages -> Sample Page.
5. Add a Homepage Posts block at the end of the page and expect it to display correctly.
6. Save the page. Then, go to Appearance -> Editor -> Pages -> Sample Page to open the same page in the site editor.
7. Expect the block to display correctly in the site editor as well.

Other information:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes, as applicable?
• Have you successfully ran tests with your changes locally?

[andrewserong]

Nice work fixing this @kevin940726! I could reproduce the issue, where the block was stuck in a loading state when viewed while editing a page within the site editor. With this PR applied, the loading state concludes and the block renders as expected in the site editor 👍

Before	After

The approach for recursively getting blocks sounds good to me, but it'd be good to get a second review / approval from @Automattic/newspack-product too 🙂