When one of the Node under Graph window is reset from the Inspector, NullReferenceException is thrown also it can't be deleted and then editor crashes when the other Node is modified, refer attached video.

Steps to repro:
1. Open attached project (VFX Graph.zip)
2. Open "New VFX" graph from the project window
3. New VFX Graph> Right-click > Create Node > Context > Update Particle
4. Select "Update Particle" Node and reset from Inspector
5. Right-click on "Update Particle" and Delete it
6. Try to delete other "Update Particle" node

Actual Result:
Editor crash on deleting reset node and NullreferenceException is throw in the console

Expected Result:
Node delete gracefully without Editor Crash and NullreferenceException

Reproducible in:
2019.3.0b7, 2019.3.0a10

Working fine in:
2020.1.0a9

Package version found: 7.1.2, 7.1.1, 7.0.0

NOTE:
Visual Effect Graph is introduced in 2019.3.0a10.

Environment:
Windows 10 & macOS 10.14