Reproduction steps:
1. Create a new or open any other project
2. Open the Shortcut Manager window (Edit -> Shortcuts)
3. In the Shortcut Manager window, search for "Scene View/" to filter the list of shortcuts
4. Find the shortcut for "Scene View/Menu"
5. Double-click on the Shortcut section for the "Scene View/Menu" row, which will make the shortcut editable
6. While the shortcut is editable, click the middle mouse button
7. Shortcut Manager will pop a window because this conflicts with another shortcut. Click the Create Conflict button
8. Shortcut Manager will set the shortcut for "Scene View/Menu" to Mouse2 (middle mouse)
9. Navigate to the Scene View and click the middle mouse button
10. A Shortcut Conflict window pops up. Select the "Scene View/Menu" row and click the Perform Selected option

Expected result: The shortcut is performed and the scene view menu is popped
Actual result: The shortcut is not performed and a NullReferenceException is logged in the Console

Reproducible with: 6000.0.38f1, 6000.1.0b6, 6000.2.0a3
Couldn’t test with: 2022.3.58f1 (No such command present in the shortcuts window)

Reproducible on: M1 Max MacOS 15.1.1, Windows 10
Not reproducible on: No other environment tested