Steps to repro:

1) Create a new VFX graph, open it

2) Add Output Mesh Block

3) Assign some new SG to its Shader property, perform Undo (notice that undo operation name is generic "VFXGraph" )

4) Observe that shader property stayed the same and an error got thrown:
{code:java}
Material 'Shader Graphs/Lit SG 1' with Shader 'Shader Graphs/Lit SG 1' doesn't have a texture property '_MainTex'
UnityEditor.Undo:Internal_CallUndoRedoPerformed (){code}