How to reproduce:
1. Open the user's attached "MicroSplat2020LTS_URP.zip" project
2. Open the "testblend" Scene
3. Select the "Terrain" GameObject in the Hierarchy window
4. Observe the Console log

Expected result: No errors are thrown
Actual result: "Material 'Hidden/InternalErrorShader' with Shader 'Hidden/Terrain_Base110911181' doesn't have a texture property '_MainTex'" error is getting spammed in the Console log

Reproducible with: 10.4.0 (2020.3.1f1), 11.0.0 (2021.1.0f1), 12.0.0 (2021.2.0a10)
Not reproducible with: 7.5.3 (2019.4.22f1)

Notes:
- Workaround is to add a _MainTex property in the Shader
- Couldn't find the exact point of regression as it was still reproducible with 10.1.0, but errors started appearing in 10.0.0-preview.26
- Was not able to reproduce the issue with the Built-in RP