[Also check case 813052 and case 797906 when resolving this]

Steps to reproduce the issue:
1. Open attached project.
2. Open scene named "testScene".
3. Enter the play mode. -- crash!

Reproduced with:
5.4.0b25, 5.4.0f1, 5.4.0f2, 5.5.0a3.
5.5.0a4 (the Editor freezes instead of crash).

Cannot reproduce with:
5.1.5f1, 5.2.5f1, 5.3.5f1, 5.3.5p8, 5.3.6f1.

Note:
Open script named "testRenderer" and temporary delete this line of code: "commandBuffer.DrawRenderer(Renderer, null);". Notice that the Editor does not crash anymore.

Crash call stack:
PPtr<Shader>::operator Shader * __ptr64
Material::GetShader
RenderingCommandBuffer::FlattenCommandBuffer
RenderEventsContext::FlattenCommandBuffers