How to reproduce:
1. Open attached project "lodRepro"
2. Open the scene "SampleScene" (Assets/Scenes/SampleScene.unity)
3. In the Hierarchy window, delete the GameObject "Cube (1)"
4. Select the GameObject "LOD Group"
5. Inspect the Console window (Window > General > Console)

Expected result: No errors are seen in the Console
Actual result: A NullReferenceException error is seen in the Console

Reproducible with: 2019.4.19f1, 2019.4.33f1
Not reproducible with: 2019.4.18f1, 2020.1.0a1, 2020.3.24f1, 2021.2.4f1, 2022.1.0a16

Error:
NullReferenceException: Object reference not set to an instance of an object
UnityEditor.SpeedTreeMaterialFixer+<EnumerateMeshRenderers>d__2.MoveNext () (at /Users/bokken/buildslave/unity/build/Editor/Mono/SpeedTreeMaterialFixer.cs:27)