sorting-desk: require a descriptor
sorting-desk: require a descriptor

Require an item descriptor when instantiating an `Item´ class since
`ItemImage´ has both content (the image's `src´ attribute) and image
data.

dossier/sortingdesk,dossier/sortingdesk,dossier/sortingdesk,dossier/sortingdesk,dossier/sortingdesk