Steps to reproduce:
1. Open the attached project
2. Open the main.unity scene
3. In Player Settings, enable Virtual Reality Support and select Windows Mixed Reality
4. Navigate to Window > Holographic Emulation and select Remote to Device as the Emulation Mode
5. Enter the HoloLens IP address in the Remote Machine field
6. Click the Connect button
7. Play the app
8. Turn off your your internet
9. Observe the crash

Actual Behavior: Unity editor crashes
Expected Behavior: Unity editor properly disconnects from the device

Reproduced with: 2017.2.0p1, 2017.2.0p3, 2017.2.0p1 MRTP 4 2017.3.0b11,
Not reproduced with: 2017.1.2p3, 2018.1.0a6
Regression introduced in: 2017.2.0p1