To reproduce:
1. Create new project with Lightweight RP template
2. Open sample scene
3. Set graphics API to Metal
4. Build and run on the device with iOS 8

Expected result: Scene launches successfully
Actual result: Player crashes

Devices:
Reproduced with: iPhone 6+ iOS 8.0, iPad Air 2 iOS 8.4
Not reproducible with iPhone 6s+ iOS 10.3.2

Unity:
Reproduced with: 2018.1.0f1, 2018.2.0b1
Earlier version don't have LW RP template.

Note: Reproduces with Metal API, both Linear and Gamma color spaces and both Mono and IL2CPP backends.

Fixed in 2018.2.6f1