“Frame-per-file rendering,” e.g. into MultiLayer OpenEXR files, at least gives you the consolation of being able to resume where you left off. I agree with trying the command-line, but also, using your chosen operating system’s “event log viewer.” When an application goes hard-down like this, it will usually leave console messages and possible tracebacks – or at least the instruction-address where the fatal exception occurred.
It is highly unusual for any modern application to outright “die.” They ought to be able to “trap” any exceptions that occur, and respond more-gracefully. (Even if they have no alternative but to terminate, which is extremely rare.)
Things to think about now:
- Do any other renders succeed?
- Do you have any previous versions of this project which didn’t crash?
- Are you keeping a “captain’s log” of your work which might help you identify a particular recent change to the project which might have introduced this problem?
- Do earlier versions of Blender also have this problem?