The best way to prevent that is to type out the chapter on Google Docs or something like that that autosaves. ...Granted that I'm too lazy for that usually so I have also occasionally lost a chapter to browser issues.
The nightmare! I'm always paranoid about doing that (knowing me, it wouldn't even be a bug, just mindlessly closing the wrong tab and forgetting about it...)
I live in constant fear! Once I’d rewritten it, I then ended up publishing by mistake AGAIN! I’m a mess!
...Granted that I'm too lazy for that usually so I have also occasionally lost a chapter to browser issues.