How to reproduce:
1. Open users attached project
2. Navigate to Assets > Bug Report and click the "mat_wall_modern_4.mat" asset
3. Observe Inspector window (assigned Shader and the material itself)
4. Click Window > Rendering > Render Pipeline Converter
5. Set to Built-in to URP
6. Select Material Upgrade and press Initialize Converters
7. Press Convert Assets
8. Observe mat_wall_modern_4 asset

Expected result: Material doesn't get converted if the Shader is broken
Actual result: Material converted and the Shader assigned to "Hidden/InternalErrorShader"

Reproducible with: 12.1.6 (2021.2.16f1), 13.1.7 (2022.1.0b13), 14.0.1 (2022.2.0a8)
Couldn't test with: 7.7.1 (1019.4.36f1), 10.8.1 (2020.3.31f1) (no Render Pipeline Converter)