PBR Validation Settings window does not open after baking the scene on selecting "Material validation options" in shading Mode. NullReferenceException throws in the console.

Steps to repro:
1. Open the attached project.
2. Wait for the lighting to finish baking
3. Navigate to Scene view > Under Scene tab click on Shading Mode.
4. Select Validate Albedo/ ValidateMetal Specular.

Actual Result:
1. PBR Validation Settings window does not open.
2. NullReferenceException throws in the console.

Expected Result:
PBR Validation Settings window opens up.

Reproducible with:
2019.3.0a2, 2019.3.0a1.

Working Fine with:
2019.2.0b1.

Notes:
- Reproduces only on Windows
- Does not reproduce on existing projects. Tested using SponzaLegacy, CornellBox, and SephoraChristmas projects.