Issue Overview

If you edit a post using Text Mode, any shared blocks will appear as though they have been deleted when you return to Visual Mode.

Steps to Reproduce (for bugs)

1. Create a new post
2. Create or insert a Shared Block
3. Switch to Text Mode
4. Make an edit, e.g. add a line of text
5. Return to Visual Mode

Expected Behavior

The Shared Block should render properly in the visual editor.

Current Behavior

The Shared Block appears as though it has been deleted.

Possible Solution

This is because RESET_BLOCKS is dispatched when PostTextEditor is blurred. This has the unintended side effect of deleting the block that the Shared Block is referencing.

One solution is to change RESET_BLOCKS so that it doesn't delete any blocks in blocksByUid that are referenced by orderedBlocks or reusableBlocks.

cc. @aduth

Screenshots / Video

Related Issues and/or PRs

#5228 introduced this bug. I discovered this while debugging #2978 which is vaguely related.