No error message in case of failure during save page

Reproduction Steps

1. Open a page and edit it
2. make sure the user cannot save the page (e.g., stop the backend server, or make sure the user does not have edit rights on the page)
3. edit some content and wait for the save to happen

Expected

An error message (as accurate as possible) is presented to the user.

Actual

No error message is displayed, making the user believe that everything went ok. But, when quitting editing, the page is back to its original content.