Regression in object browser Volto 18?

[fredvd]

The object browser for main (Volto 18) seems to have a bug. Except for the single item select, multiple select and other storybooks show the following error for the object browser widget. In a project where we try multiple select we see similar issues:

https://6.docs.plone.org/storybook/?path=/story/edit-widgets-object-browser--placeholder

[davisagli]

@fredvd I couldn't reproduce it on main using the related items field.

It's not immediately obvious to me what causes the error. It looks like it would happen if the object browser nav component is passed a value for selected which is truthy but not an Array.