Force closed designer after infite loop - days worth of progress lost

As you can probably deduct from the title - I've made a rookie mistake..

After accidentally locking my entire designer up by starting preview mode before finishing my script, I force-closed it via task-manager.
Expecting to have lost my changes since the last time I saved, it turns out I lost all changes since the last time I closed the designer.

When opening back up again, I got notified 'another user' was working in the same project and saving could result in conflict. I started to take stock of what exactly I hadn't saved since earlier this afternoon, but discoverd all my changes of the past days (since I've opened the designer, essentially) had been lost instead.

As the designer seems to think 'another user' is still working in the project, is there a way for me to retrieve what was lost, do I wait until the session times out, or am I just going to have to redo the last 3 days' worth of work?

Wait for the timeout. Should not be long. Grab a gateway backup while you wait.

(Use git or regularly take gateway backups to capture forward progress.)

It was, in fact, not long. I've grabbed a back-up and from what I can tell only some graphic updates from this afternoon were lost - not the scripts I've spent the last three days on. Thank you.

Is there a way to exit preview mode besides the toolbar-button? In case I make another oopsie ..

No, infinite loops are infinite. Unless in the script console. I think ctrl-C does work there. Or there's a kill button. (Can't remember the last time I did similar.)

Both do, yes.