Block Hooks: Not properly working with Classic block in Post Content (first/last child insertion)

[ockham]

Description

As reported by @gziolo here:

One thing that might need closer look is when using the Classic block in the post content. I couldn't make it work with inserting the hooked block as the last or first child in the core/post-content block.

Step-by-step reproduction instructions

TBD

Screenshots, screen recording, code snippet

Environment info

No response

Please confirm that you have searched existing issues in the repo.

• Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

• Yes

Please confirm which theme type you used for testing.

• Block
• Classic
• Hybrid (e.g. classic with theme.json)
• Not sure

[t-hamano]

Is this a recent issue? If so, we can add this issue to the 6.8 project board.

[ockham]

@t-hamano Yes, this was found by @gziolo when reviewing my other bugfix. I think we should add it to the 6.8 board 👍

I won't be able to work on a fix this week, but I'll look into it next week.