I am also hitting this bug in my VR project in version 4.18.1. I had not seen it in version 4.15.3. There seems to be no clear repro or correlation with any particular behaviour, as sometimes it runs without crashing, while other times it will crash within 1-2 minutes of use.
My only real repro steps are to run the project and Play in VR Preview, stop the play session, and repeat. NathanSculptrVR’s hints that it might be to do with the debug output seem as likely as anything else, but I can’t confirm this especially as debug output is frequent enough in my project that there’s always a recent bit of output prior to the crash.
Not sure how helpful any of this is, but I wanted to flag that it’s happening for me too and hope a fix can be found.