I believe you are correct with this theory. From my experimenting it seems to happen when the phone hands over from WiFi to mobile data and the mobile data connection is not active in the background.
An easy way to replicate this is to go in to Developer options > mobile data always active and disable this setting.
After doing this you will see when the phone looses the WiFi connection and tries to hand over to mobile data the crash happens: https://www.youtube.com/watch?v=j1iQqvtnhbQ (watch the WiFi icon disconnect and mobile data come back online)
Likewise when I know mobile data is inactive in the background I can replicate this by simply switching WiFi off: https://www.youtube.com/watch?v=ztbA8aFei7o