Library: Incorrect snackbar text and sidebar menu when removing template/template part

[t-hamano]

Description

I believe the following behavior that occurs when a template part is deleted is not what was intended.

• Displayed as "undefined" deleted. on snackbar.
• Nothing appears in the side menu.

Step-by-step reproduction instructions

• Access the Site Editor > Library.
• Click "Create pattern" button > Select "Create template part"
• Create template part.
• Click the document title bar.
• Select "Delete template part".
• A snackbar with the text "undefined" deleted. should appear. Also, nothing will appear in the sidebar menu.

Screenshots, screen recording, code snippet

27cbe95fc24791a2bdf325d7097a05a4.mp4

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

[t-hamano]

I have confirmed that this problem occurs with template as well as template part.

7be1728d8ee8385e5d29ee0d172e81c8.mp4

[aaronrobertshaw]

It appears that the entity record received when deleting via the List page vs the command palette is slightly different.

On the List page, the record contains a template.title.rendered property which is what the removeTemplate action expects, hence the correct snackbar notice there. The record passed on from the command palette only contains a simple string for the template.title property.

I haven't put my finger on why there's a difference just yet but will keep digging.

[aaronrobertshaw]

This was fixed in #52034.