Steps to reprodue:

1. Open attached project
2. Switch to iOS and make a build
3. Deploy to device
4. When launched, tap 'GetPixels' button to call WebCamTexture.GetPixels and create a texture from it
5. Tap 'Change Scene' to load a different scene
6. Notice the game crashes

Reproduced with: 2017.1.4f1, 2017.4.13f1, 2018.3.0b6

Tested with:
iPhone 5S (iOS 9) - Reproduced
iPhone SE 9iOS 10) - Reproduced
iPhone 8 (iOS 11) - Reproduced
iPhone XS Max (iOS 12) - Reproduced

Notes: The game crashes even if you call WebCamTexture.GetPixels without creating a texture and applying it to an actual image, these were just added for a more clear repro.