Fix: stale missing blocks after persisted CRDT restore - #78036

#77796

What?

Closes

This PR invalidates persisted CRDT blocks when they contain a core/missing block whose original block type is now available again.

Why?

When a block type is unavailable, Gutenberg renders it as core/missing.

With RTC persistence enabled, that stale core/missing state can be restored from the persisted CRDT document after the block type becomes available again. The editor then keeps rendering core/missing after reload, even though the block type is registered.

How?

The persisted CRDT block comparison now also checks whether any restored core/missing block has an originalName that is currently registered.

Testing Instructions

1. Install and activate a plugin that registers custom blocks, such as WooCommerce.
2. Create a page.
3. Add a WooCommerce block, for example the Cart Link block.
4. Save the page.
5. Deactivate WooCommerce.
6. Reload the editor.
7. Confirm the block renders as a missing block.
8. Reactivate WooCommerce.
9. Reload the editor.
10. Confirm the block is restored as the WooCommerce block instead of remaining core/missing.

Testing Instructions for Keyboard

Screenshots or screencast

Use of AI Tools