In my long ago case, something/someone must have been killing the main process without killing the children. But I'm fairly certain it didn't do any harm - certainly didn't corrupt databases, I'd remember that.
I suspect I was doing something a bit odd, I don't recall posting anything here about it. Was in my early calibre days.
All I can suggest is to run frequent library checks and take regular backups - but I suspect you don't need me to tell you that
BR