Re: SteamVR crashes when exiting game
May have found a solution.
After some digging online someone suggested that a program called Natural Locomotion can sometimes cause the error (although in general, not just in Squadrons in particular, and I wasn't having issues with any other game) due to the driver they use.
I've never actually used the program, but I did have the demo installed on my Steam account. I don't believe it was automatically launching with SteamVR (like fpsVR etc), but I uninstalled it anyway.
Then booted up Squadrons and, touch wood, after starting and exiting the game three times, it appears to have stopped crashing! (Worked both from launching the game from SteamVR Home as well as directly with "launch as VR" from the Steam desktop application)
Caveat:
Unfortuantely, the first time I booted SteamVR after removing the demo, there was a headset update so there's the possibility it was the update that fixed it and not removing the program. I wanted to reinstall the demo to see if I could replicate the issue and prove the cause, but it appears the demo is no longer available for install on Steam (only the full paid version) so without actually buying it I can't verify for sure.