Creating a page with a page definition which references a dialog that does not exist, Magnolia does not throw any error and does not create any page.

Steps to reproduce

In LM reference in page definition dialog that does not exist.
Try to create page with that template.

Expected results

Error is throw telling that reference dialog is not existing.

Dev note: Throw exception visually and then problem in definition should be enough. 

Actual results

Page is not created.
There is no visual feedback.
Nothing really happens
See attached video.

Development notes

Check in Definition app that the problem is shown about dialog actually missing