WP Views need to load some sort of "no items found" placeholder view if the item(s) needed for the preview are not found

[gcorne]

WP Views work by replacing the shortcode with a placeholder that is then filled with a preview after data is retrieved for the view via ajax calls. If there isn't any data, we need to populate the preview with some sort of "no items found" content body so that the view can be edited and is visible.

[gcorne]

27558-01.patch​ adds a "No items found." state which is displayed when rendering the gallery wpview when no attachments are found and an ajax call to fetch attachments is not in progress.

[gcorne]

Look-and-feel of gallery with no items found

[azaozz]

In 27899:

Gallery preview: add a "No items found" state which is displayed when rendering the gallery wpview and no attachments are found. Props gcorne, fixes #27558