The recursive template parts in Fizzie break Gutenberg's Template parts block

[bobbingwide]

I wanted to test my rich text localization ( l10n) logic in Gutenberg 9.5.1 so I created a template part called i18n-rich-text.html.
I tried to load it using the Template part block in a page, while in the bb_BB locale.

But in s.b/wp56 I got This block has encountered an error and cannot be previewed even before I had a chance to pick the template part.
I believe this was due to the Template part block trying to display Previews of the blocks and failing to detect recursion.

Note: In s.b/wp55/tt1 - with the recursive template parts I'd created for Twenty Twenty-One Blocks it causes Chrome to time out.

Clearly there's a problem with the Template parts block ( core/template-part ).
But what should I do as a workaround?

[bobbingwide]

Workaround

Edit one of the template parts so that it doesn't go recursive.
This can be done by removing the blank space between the block name and the attributes.
eg

<ul>
    <li>Issue-30 test case.
    <!-- wp:template-part{ "slug": "issue-27", "theme": "fizzie" } /-->
    </li>
</ul>

[bobbingwide]

Template parts can no longer be inserted in the block editor.
They can be inserted in the Site Editor.
I reverted issue-30.html and tested in the Site Editor.
The recursion detection logic in Gutenberg worked. It was fixed in March 2021.