Files field query is invalid

I have a field like this in my site blueprint:

openGraphImage:
  type: files
  multiple: false
  query: page.images
  required: true
  translate: false

The query here triggers the following error in the panel:

Your query must return a set of files

However this query seems correct according to the Kirby docs.

What am I doing wrong?

You dont need the query at all, the default is to show all the files on the page. Unless…do you have other file types on the page and you just want to show images in it?

That’s the idea, I want to allow only images to be selected.

If you want to restrict the type of images that can be uploaded to the page via this field, you have set the upload property with a template that contains an accept property.