Prevent data loss issues in text editor

Note: all this happened on a private wiki, with HTTPS enabled. I was using the wiki editor, but the same thing would have happened in the WYSIWYG editor.

Case 1: working on a document I had just created from a template, forgot to regularly save and continue, hit the wrong keyboard shortcut in Firefox, got send to the previous page. Tried to go back to the next page, the template was reused, all my previous content was lost.

Case 2: working on a document created from a template again, my internet connexion dropped in the background. I didn't notice that it was off when hitting "save and continue". When clicking "Save and view" I got an "Internet is not working" message from Firefox. I restored the connexion and went back, but again my content was lost, replaced by that of the template.