How to reproduce:
1. Open the attached project named "skytest.zip"
2. Open the "samplescene" Scene
3. Select the Sky and Fog Volume object
4. Check if the Sky Reflection Size setting in the HDRP asset is set to 4096
5. Try changing the Exposure setting in the HDRI tab

Expected result: Exposure of the sky changes
Actual result: Unity crashes right after changing the exposure setting

Reproducible with: 2019.3.0f1, 2019.3.0f5, 2020.1.0a20
Not reproducible with: 2018.4.16f1, 2019.2.19f1, 2019.3.0b12
Could not test with: 2017.4.36f1(HDRP was not yet available)

Reproducible with package versions: 7.1.6, 8.0.0
Not reproducible with package versions: 4.10.0, 7.1.5

Notes:
1. HDRP 7.1.6 was introduced in Unity 2019.3.0f1