[VFX graph] NullReferenceException is thrown when saving the graph

NullReferenceException is thrown when saving the graph with the Save button in the VFX graph.

Steps to Repro:
1. Create a new Project
2. Add Visual Effect Graph Package
3. Create a new VFX Graph and open it
4. Save the Graph
5. Observe the NullReferenceException in Console.

Expected Result: Graph is saved without throwing errors

Actual Result: NullReferenceException is thrown.

Reproducible in: 2021.2.0b1 (12.0.0)
Working Fine in: 2021.2.0a21 (12.0.0)

Environment: Windows 10 and macOS 11.3

Note: No errors are thrown when the graph is saved using CTRL + S

Stack trace: NullReferenceException: Object reference not set to an instance of an object
UnityEditor.VFX.UI.VFXComponentBoard.DeactivateBoundsRecording () (at library/packagecache/com.unity.visualeffectgraph@12.0.0/editor/graphview/vfxcomponentboard.cs:354)