“NullReferenceException: Object reference not set to an instance of an object” error is thrown after installing Project Auditor Rules when Search window is open

Reproduction steps:
1. Create a new project
2. Click on "Global Search" button in the top Editor toolbar to open Search window
3. Window > Analysis > Project Auditor
4. Click “Install Rules” button
5. Observe the Console

Actual result: “NullReferenceException: Object reference not set to an instance of an object” error is thrown
Expected result: No error or warning is thrown

Reproducible with: 6000.5.0a7
Not reproducible with: 6000.5.0a6
Couldn’t reproduce with: 6000.0.68f1, 6000.3.9f1, 6000.4.0b9 (No “Install Rules” button)

Reproduced on: Windows 11, macOS Sequoia 26.2 (M4)

Note:
Full error:

NullReferenceException: Object reference not set to an instance of an object
UnityEditor.Search.SearchWindow.Update () (at /Users/bokken/build/output/unity/unity/Modules/QuickSearch/Editor/UITK/SearchWindow.cs:167)
UnityEditor.HostView.SendUpdate () (at /Users/bokken/build/output/unity/unity/Editor/Mono/HostView.cs:712)
UnityEditor.EditorApplication.Internal_CallUpdateFunctions () (at /Users/bokken/build/output/unity/unity/Editor/Mono/EditorApplication.cs:403)