Unity Crash Reporting / Debugging

I've had a couple of Windows users report crashes when trying to launch the game I'm working on (Grave Days). It makes me a little nervous and I don't have a good strategy to debug the issue and our Steam Early Access launch is coming up quickly. One person who reported the crash has been willing to help me out by digging around a bit and trying things out, but no luck so far. The player log file doesn't show anything suspicious and just ends silently after a couple of expected debug messages. I've asked him to look for a crash dump file, but there wasn't one produced. Even stranger, he did get the game to start-up once, and could navigate the menus a bit, but then it just crashed again and never recovered again.

I suspect this type of issue can probably be caused by driver issues on the user's system, a Unity bug, an audio engine bug (we use Wwise). I'm also making all builds from my linux dev machine, so maybe there's an issue there.

I've noticed on Godhood's steam community page that the dev mentioned to a player that they found the crash report on their backend, so just wondering what solutions there are for this? Bug reports are of course easy, but how do you catch and report a crash in Unity?

Any advice will be appreciated!