Can not delete a GTK Context Node when it is duplicated with one or more Blocks

How to reproduce:
1. Extract and open the attached “IN-136013.zip“ project
2. Double-click the “Assets/Data/Items/Weapons/PhoenixFeather/PhoenixFeather_Behavior_Active.ibg“ asset
3. Right-click in the opened “PhoenixFeather_Behavior_Active“ window
4. Select “Add Node“
5. Add the “LevelingContextNode“
6. In the “LevelingContextNode“ click “Add a Block“
7. Add the LevelMilestone Block
8. Right-click the “LevelingContextNode“
9. Click on “Duplicate”
10. Right-click the duplicated “LevelingContextNode“
11. Click on “Delete“
12. Observe the Console and the “PhoenixFeather_Behavior_Active“ window

Actual result: It is not possible to delete the Context Node, and a “NullReferenceException: Object reference not set to an instance of an object“ error message appears
Expected result: The Context Node gets deleted, and no error messages appear

Reproducible with: 0.1.0-exp.1, 0.4.0-exp.2 (6000.3.11f1)
Could not test with: Could not get the asset to load in different Editor versions

Reproducible on: Windows 11
Could not reproduce on: No other environment tested