Similarly, my Unreal Editor (v4.19) was crashing when running VR Preview every 2nd time.
Issue:
The source of the issue, in my case, was having in the “Project Settings” the “Default Game Mode” set to a game mode which was used for the default game level in multiplayer environment, meaning it was trying to set up a server/client environment.
Solution:
Edit “DefaultEngine.ini” and modify the line “GlobalDefaultGameMode=[yourGameMode]” to “GlobalDefaultGameMode=None”, or whichever other game mode which would not crash the VR-Preview.