How to reproduce:
1. Open the user's attached "Crystals2D.zip" project
2. Open the "ChainVFX" VFX Graph (Assets -> VFX)
3. Open the "ChainShader" Shader Graph (Assets -> VFX)
4. Add a variable into the "ChainShader" Shader Graph
5. Save the Asset

Expected result: Changes are saved
Actual result: Editor crashes

Reproducible with: 12.0.0 (2021.2.0b1, 2021.2.0b4, 2022.1.0a3)
Not reproducible with: 7.6.0 (2019.4.29f1), 10.6.0 (2020.3.14f1), 11.0.0 (2021.1.17f1), 12.0.0 (2021.2.0a15)
Could not test with: 2021.2.0a16 - 2021.2.0a21 (Shader Graph is broken for some reason)

Note:
- The issue is also reproducible if you open the VFX Graph after making changes to the Shader Graph that is applied in the VFX Graph