Steps to reproduce

1.  Create folder a and b in Asset app like images 
2.  Open Pages app and edit any template has chooser link to existing image
3. Expand a and b
4. Collapse a and others like stories-demo (parent of selecting image) does not work

.. Logs, screenshots, gifs...

Expected results

Collapse a and others like stories-demo (parent of selecting image) must work

Actual results

Workaround

Close dialog, open again, don't expand "b"

Development notes

The expand icon is displayed for empty folders, making Vaadin freeze on click:

public boolean info.magnolia.dam.app.data.HierarchicalAssetDataProvider#hasChildren(Item item) {
 return item.isFolder();
}