Unable to open Shader Graph Editor when clicking on "Open Shader Editor" in the ShaderSubGraphImporter

Steps to Reproduce:
1. Create a new Project with HDRP Template
2. Install Package Manager > HDRP package > 7.2.1
4. Create Assets > right-click > Shader > PBR Graph
5. Create new node from New Shader Graph window > PBR Master > Vertex Position > Artistic > Adjustment > Channel Mixer
6. Select Shader Graph window > Channel Mixer > right-click > Convert To SubGraph
7. Click on NewShaderSub Graph > Inspector > Preset
8. Click on Assets > NewShaderSubGraphImporter > Inspector > Open Shader Editor

Expected Result:
Either Open Shader Editor option not presented or Editor opens up

Actual Result:
Editor does not open

Reproducible on: 2020.1.023, 2019.3.2f2, 2019.2.12f1, 2019.1.14f1, 2018.4.17f1

Environment: Windows 10 and Mac 10.14