NullReferenceException: Object reference not set to an instance of an object
UnityEditor.HostView.DeregisterSelectedPane (System.Boolean clearActualView, System.Boolean sendEvents) (at /Users/builduser/buildslave/unity/build/Editor/Mono/HostView.cs:444)
UnityEditor.HostView.SetActualViewInternal (UnityEditor.EditorWindow value, System.Boolean sendEvents) (at /Users/builduser/buildslave/unity/build/Editor/Mono/HostView.cs:38)
UnityEditor.HostView.set_actualView (UnityEditor.EditorWindow value) (at /Users/builduser/buildslave/unity/build/Editor/Mono/HostView.cs:31)
UnityEditor.DockArea.OnEnable () (at /Users/builduser/buildslave/unity/build/Editor/Mono/GUI/DockArea.cs:161)
UnityEditorInternal.InternalEditorUtility:LoadSerializedFileAndForget(String)
UnityEditor.WindowLayout:LoadDefaultWindowPreferences() (at /Users/builduser/buildslave/unity/build/Editor/Mono/GUI/WindowLayout.cs:40)