"You may not pass null objects" and "Maximized serialized file backup not found" errors are thrown when maximizing and minimizing docked Multiplayer Play Mode window after Multiplayer Play Mode package is uninstalled

Reproduction steps:
1. Create a new project
2. Install Multiplayer Play Mode package (Window > Package Management > Package Manager)
3. Window > Multiplayer > Multiplayer Play Mode
4. Dock the Multiplayer Play Mode window anywhere (e.g. in the Inspector window)
5. Uninstall Multiplayer Play Mode package
6. Double-click the window tab where Multiplayer Play Mode window was docked to maximize it
7. Double-click on the tab again to minimize the window
8. Press "Continue" in the "Revert All Window Layouts" pop-up and observe the Console

Actual result: Layout restarts, "You may not pass null objects" and "Maximized serialized file backup not found" errors are thrown
Expected result: No errors are thrown and the window layout is restored to the state it was in before maximizing

Reproducible with: 2.0.0-pre.1 (6000.3.0a6), 2.0.2 (6000.5.0f1), 3.0.0 (6000.6.0a7)
Not reproducible with: 1.6.3 (6000.0.76f1)

Reproduced on: macOS Tahoe 26.5 (M4), Ubuntu 24.04

Note:

• After step 5, Multiplayer Play Mode and other docked windows disappear and "Failed to load" text appears on the tab
• Not reproducible with other package specific windows (e.g. Recorder, Addressables Groups)
• Full errors:

You may not pass null objects
UnityEngine.StackTraceUtility:ExtractStackTrace ()
UnityEditorInternal.InternalEditorUtility:SaveToSerializedFileAndForgetInternal (string,UnityEngine.Object[],bool)
UnityEditorInternal.InternalEditorUtility:SaveToSerializedFileAndForget (UnityEngine.Object[],string,bool) (at /Users/bokken/build/output/unity/unity/Editor/Mono/InternalEditorUtility.bindings.cs:348)
UnityEditor.EditorApplication:Internal_CallDelayFunctions () 

Maximized serialized file backup not found.
UnityEditor.GUIView:ProcessEvent (UnityEngine.EntityId,intptr,bool&) (at /Users/bokken/build/output/unity/unity/Editor/Mono/GUIView.cs:70)