Steps to reproduce:

1. Open the attached project
2. Open Multiplayer Play Mode window 
3. Start one of the Virtual Players
4. Open the Package Manager window
5. Change the version of the MPPM package (If no versions are listed under Version History tab - use the add Package by name option and provide a different version than it is currently installed
6. After the upgrade process is over, inspect the Virtual Player's window
7. Try closing the Virtual Player's window

Actual results: Depending on the MPPM package version, errors will appear immediately after opening the VP window or after trying to close it. On the newer MPPM version, the bug also prevents the window from being closed

Expected results: The package version change proceeds without issues. MPPM windows are either gracefully closed or remain open and functional after the upgrade process.

Reproducible with versions: 1.1.0(6000.0.6f1), 1.2.0, 1.2.2(6000.0.10f1), 1.3.3(6000.0.46f1), 1.4.0(6000.1.0b13), 1.4.1(6000.1.0b14, 6000.2.0a8), 1.5.0-exp.1(6000.2.0a8)

Not reproducible with versions: 1.0.0-pre.2, 1.0.0(6000.0.0b11)

Tested on (OS): macOS 15.3.2

Notes:

• While testing 1.2.0-1.2.2 errors appeared immediately after opening the VP's window. The bug did not prevent closing the VP window
• While testing 1.4.0-1.5.0-exp.1 errors appeared only when trying to close the VP window. The bug prevents the window from closing. The only way to close it is either to restart the editor or enter Play mode which crashes the leftover VP window

Full error message:
{quote}FileNotFoundException: Could not find file ""
System.IO.Directory.InsecureGetCurrentDirectory () (at <90608de5b7464836a1b66c3d03851b52>:0)
System.IO.Path.InsecureGetFullPath (System.String path) (at <90608de5b7464836a1b66c3d03851b52>:0)
System.IO.Path.GetFullPath (System.String path) (at <90608de5b7464836a1b66c3d03851b52>:0)
System.IO.Directory.CreateDirectory (System.String path) (at <90608de5b7464836a1b66c3d03851b52>:0)
UnityEditor.WindowLayout.EnsureDirectoryCreated (System.String path) (at /Users/bokken/build/output/unity/unity/Editor/Mono/GUI/WindowLayout.cs:1116)
UnityEditor.WindowLayout.SaveWindowLayout (System.String path, System.Boolean reportErrors) (at /Users/bokken/build/output/unity/unity/Editor/Mono/GUI/WindowLayout.cs:1608)
Unity.Multiplayer.PlayMode.Editor.Bridge.WindowLayout.SaveWindowLayout (System.String path) (at ./Library/PackageCache/com.unity.multiplayer.playmode@9270179de68a/InternalBridge/WindowLayout.cs:28)
Unity.Multiplayer.Playmode.Workflow.Editor.ModeSwitcher.SaveCurrentWindow () (at ./Library/PackageCache/com.unity.multiplayer.playmode@9270179de68a/Workflow/Editor/EditorModes/ModeSwitcher.cs:110)
Unity.Multiplayer.Playmode.Workflow.Editor.ClonedPlayerSystems+<>c.<Listen>b__14_2 (System.Boolean isFocused) (at ./Library/PackageCache/com.unity.multiplayer.playmode@9270179de68a/Workflow/Editor/EditorSystems/ClonedPlayerSystems.cs:122)
UnityEditor.EditorApplication.Internal_FocusChanged (System.Boolean hasFocus) (at /Users/bokken/build/output/unity/unity/Editor/Mono/EditorApplication.cs:554)
{quote}