Widget Importer: Extra "import" button visible when there's nothing to import

[annezazu]

Description

When there's nothing to import and you add a new template part, an extra "import" option appears that is always in a disabled state.

I also noticed the import option is under "Advanced" rather than at a top line level. This feels a bit hidden and I'm not sure why/where that decision was made but wanted to note!

Step-by-step reproduction instructions

1. Create a new site using a block theme.
2. Open the Appearance > Editor.
3. Add a new template part.
4. Notice there's an import button visible despite there being nothing to import.

Screenshots, screen recording, code snippet

When there's nothing to import:
https://user-images.githubusercontent.com/26996883/218203172-e6332fe2-458d-41cc-95ef-4e299a274b0a.mov

When there's something to import:

Environment info

• WordPress 6.2 beta 1
• No GB installed
• TT3

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

[annezazu]

Noting that this still appears with beta 3 but it has slightly changed:

[Mamaduka]

I’ve a potential fix and will push it tomorrow.