"NullReferenceException: Object reference not set to an instance of an object" error is thrown when opening the Add Node window in the Behavior Graph by pressing Space key

How to reproduce:
1. Open the “NorthShoreUnity” project
2. Add new Behavior Graph in the Assets folder (Create → Behavior → Behavior Graph)
3. Open the created Behavior Graph
4. Press the Space key on the keyboard
5. Observe the Console and Behavior Graph

Expected result: No errors are displayed in the Console, and the Add Node window opens successfully
Actual result: The "NullReferenceException" error is displayed in the Console, and the Add Node window is not opening.

Reproducible in: 1.0.3 (6000.0.27f1, 6000.1.0a5), 1.0.5 (6000.0.27f1, 6000.1.0a5)

Reproducible on: Windows 10, Windows 11 (user’s)
Not reproducible on: No other environments tested