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

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?

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

It also gets:
additionalProjects.0.shortname: This value should not be blank.
additionalProjects.0.version: This value should not be blank.

I was previously on someone else's now-expired 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 how to do it.

Sorry, accidentally posted my screenshot to the wrong field. Correcting.