- Open new Pages app
- Create page
- Click Add page
- Leave template select field or page title (or both) empty
- Press Next
Observe red banner behind dialog appearing (as in included screenshot)
Only "This field is required" should show.
Add page button from action bar becomes disabled in effect, one has to click on some page to re-enable it.
Stacktrace and video demonstration (credit: mdrapela) included as attachments.