Error "additionalProjects.0.shortname: This value should not be blank." when launching sandbox

Now I've had a coffee I realise you don't need to add CKEditor5 as an additional project with Drupal 9.5.11. However, the error message here is still confusing so I'll leave the issue open and let the maintainers decide whether to close it.

Oh - that’s an interesting one!

We have made a few changes recently (preparation for moving it to D10) but this doesn’t seem connected.

This is adding the 1.0-dev release of ckeditor5, right?

Yes

So, in an ideal world, the combination wouldn’t be selectable because a composer.json and module.info.yml would say that Drupal/ckeditor5 was not compatible with versions 9.5.0 upwards.

If that was the case, we’d never get to the point of attempting to install (and, therefore, needing a better error message that’s buried in the depths of React code where dragons hang out…)

Is that even possible?

Not sure whether this is a separate issue, but I'm getting the same errors today for:

Drupal core (10.2.5)
and
Additional project name:
Navigation 1.x-dev

I was on someone else's Tugboat site which had Navigation installed, so evidently there is a way to create it, but simply adding Navigation 1.x-dev, which I chose from the autocomplete drop-down, does not seem to be it.

Sorry, accidentally po