Jira: https://jira.unity3d.com/browse/GFXGI-500

Reproduction steps:
1. Create an empty project
2. In the Hierarchy window, create a new Reflection Probe
3. In the Inspector window, select Bake
4. In the Hierarchy window, create a new Reflection Probe again
5. In the Inspector window, select Bake
6. Observe the Console window

Expected result: There are no errors and the Reflection Probe is baked
Actual result: "PPtr cast failed when dereferencing! Casting from ScriptMapper to Texture!" error appears

Reproducible with: 2019.4.0f1, 2019.4.20f1, 2020.2.7f1, 2021.1.0b9, 2021.2.0a7
Not reproducible with: 2018.4.32f1, 2019.3.16f1

The error is different with different Unity versions:
1. With 2019.4.20f1 it is "PPtr cast failed when dereferencing! Casting from ScriptMapper to Texture!"
2. With 2020.2.0a1 - 2021.2.a7 it is "PPtr it is cast failed when dereferencing! Casting from Shader to Texture!"