Can't add new Contact Page component

[Adnan-cds]

How to reproduce

• Open /admin/content/paragraphs/add/default
• Select "Add Contact" from the only dropdown in the page.
• Nothing happens. A Contact Paragraph creation form should have appeared.
• Ajax error message appear in the browser's Javascript console.
• PHP exception logged in Drupal's log: TypeError: Argument 1 passed to Drupal\Core\Render\Element::children() must be of the type array, null given, called in /path/to/localgov-project/web/core/themes/claro/src/ClaroPreRender.php on line 87 in Drupal\Core\Render\Element::children() (line 71 of /path/to/localgov-project/web/core/lib/Drupal/Core/Render/Element.php)
• All works fine if I switch to the "Seven" admin theme.

Needs some digging in to find out what's happening inside the Gin/Claro themes.

@finnlewis @MattOz-CDS @stephen-cox @danchamp

[danchamp]

@Adnan-cds We came across this in Cumbria, it's a known issue for paragraph types with vertical tabs in Claro:

https://www.drupal.org/project/drupal/issues/3223319

Changing tabs to horizontal for the Contact paragraph type fixed it for us, I haven't tried the recent patch in the Drupal project issue.

[danchamp]

Sorry, I thought I'd raised issues for everything like this we came across, but this one slipped through the net.

[Adnan-cds]

Thanks Dan. Good to know it's a core bug.

[Adnan-cds]

The patch attached to the d.o ticket is outdated. A little tweak makes it usable, but I am unsure if the logic in the patch is fully reliable given there has not been much discussion around it yet. Telling the Contact Paragraph to use a Horizon tab in its form display works as you have said, but then its form looks odd. I am wondering what to do. @danchamp

[Adnan-cds]

No longer an issue following a core fix.