How to reproduce:
# Create a new graph and add it to the scene
# Add custom HLSL block to Update context
# Save graph

Observe that vfx is no longer rendered and error is thrown to the console

Note: couldn't repro on 2023.3.0a3

Unity cannot compile the VisualEffectAsset at path "Assets/TEST hlsl/Main Graph.vfx" because of the following exception:
UnityEngine.UnassignedReferenceException: The variable m_ShaderFile of CustomHLSL has not been assigned.
You probably need to assign the m_ShaderFile variable of the CustomHLSL script in the inspector. at UnityEngine.Object+MarshalledUnityObject.TryThrowEditorNullExceptionObject