Steps to reproduce:

1. Create a new Unity project
2. Make sure the AI Assistant package/s are installed
3. Click the "AI" button, which is displayed in the toolbar next to the "Unity version Control" button
4. Click the "Open Assistant" option
5. Verify that the window opens
6. Click the "Attach" button, which is displayed at the bottom of the window
7. Enter "test" into the search field in the window and click "Enter"
8. Close the window
9. Observe the "Console" view

Actual results: User gets an error "NullReferenceException: Object reference not set to an instance of an object" in the Console window. A short video is added below in the "Attachment" area.

Expected results: No errors

Reproducible with versions: 1.0.0-pre.3 (6000.2.0b1)

Not reproducible with versions: -

Can’t test with versions: -

Tested on (OS): M1 Max - Sequoia 15.4.1

Notes: Full error

NullReferenceException: Object reference not set to an instance of an object
Unity.AI.Assistant.UI.Editor.Scripts.Utils.PopupTracker.Dispose () (at ./Library/PackageCache/com.unity.ai.assistant@95cd11640ec5/Editor/UI/Scripts/Utils/PopupTracker.cs:97)
Unity.AI.Assistant.UI.Editor.Scripts.Components.AssistantView.HideSelectionPopup () (at ./Library/PackageCache/com.unity.ai.assistant@95cd11640ec5/Editor/UI/Scripts/Components/AssistantView.cs:583)
Unity.AI.Assistant.UI.Editor.Scripts.AssistantWindow.OnLostFocus () (at ./Library/PackageCache/com.unity.ai.assistant@95cd11640ec5/Editor/UI/Scripts/AssistantWindow.cs:50)
UnityEditor.HostView.OnLostFocus () (at /Users/bokken/build/output/unity/unity/Editor/Mono/HostView.cs:355)
UnityEditor.DockArea.OnDestroy () (at /Users/bokken/build/output/unity/unity/Editor/Mono/GUI/DockArea.cs:141)
UnityEditor.ContainerWindow:RequestCloseSentByNativeCode() (at /Users/bokken/build/output/unity/unity/Editor/Mono/ContainerWindow.cs:443)