Steps to reproduce

1.  Create a multiValue field which fields are damLinkField type

   form:
     properties:
       downloads:
             label: Downloads
             $type: jcrMultiValueField
             field:
               $type: damLinkField
               label: Download 

2. Create the component, clic on "add" button but do not select any image (just create the damLinkField and let it empty)
3. Save the dialog
4. Open the component and check that it throws an error (and component is never opened again)

Expected results

DamLinkField is created with empty value, so when it opens it has no image selected.

Actual results

Dialog is saved but when you try to open it, can exception is thrown (check attachments)

Workaround

Include required: true at the damLinkField so you must select an option before saving the dialog

Development notes

Without being nested on the multiValueField (e.g, a simple damLinkField componente), it allows to save an empty dam selection without launching any error on re opening.