"NullReferenceException thrown in BootstrapManager.OnGUI after pressing "Server" in Netcode for GameObjects Bootstrap sample" in Play mode

Steps to reproduce:
1. Create new Unity project using Universal 3D Template
2. Open Package Manager and install “com.unity.netcode.gameobjects” package
3. Once installed, open Samples tab and import “Bootstrap” Sample
4. Open Bootstrap scene (Assets > Samples > Netcode for Objects > 2.13.1 > Bootstrap > Scene)
5. Enter Play Mode
6. Press “Yes” in “Add Scene to Scenes in Build” pop-up
7. In Game View press on “Server” button
8. Exit Play Mode
9. Observe the Console window

Actual results: “NullReferenceException” and curl errors are thrown in the Console window after exiting Play Mode

Expected results: No errors are thrown in the Console window

Reproducible with versions: 2.13.1 (6000.0.81f1, 6000.3.23f1, 6000.5.10f1, 6000.6.0b10, 6000.7.0a5)

Tested on (OS): macOS Tahoe 26 (M1)

NullReferenceException: Object reference not set to an instance of an object
Unity.Netcode.Samples.BootstrapManager.OnGUI () (at Assets/Samples/Netcode for GameObjects/2.13.1/Bootstrap/Scripts/BootstrapManager.cs:16)
UnityEditor.GUIView:ProcessEvent(EntityId, IntPtr, Boolean&) (at /Users/bokken/build/output/unity/unity/Editor/Mono/GUIView.cs:86)

Curl error 3: URL rejected: Error