Sprite Renderer displays a warning when attempting to use URP shaders

Steps to reproduce:

1. Download and open the attached project ([Internal link])
2. Open the SampleScene
3. Select the Sprite Renderer GameObject

Expected result:

• No error is shown in the Sprite Renderer component when using URP shaders

Actual result:

• An error is show when using URP shaders in the Sprite Renderer (see attached screenshot)

Notes:

• Reproduces in all public Unity builds
• Reproduces in URP only; other RPs are unaffected
• URP shaders use _BaseMap property for albedo textures instead of _MainTex. Perhaps it would make sense to store _MainTex in URP shaders as well, but hide it in the inspector