Open any project and click the Gizmos button in the GameView window.
See exception in Console:
"ArgumentNullException: Argument cannot be null.
Parameter name: key
System.Collections.Generic.Dictionary`2[System.Type,System.Type].TryGetValue (System.Type key, System.Type& value) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Collections.Generic/Dictionary.cs:588)
UnityEditor.CustomEditorAttributes.FindCustomEditorTypeByType (System.Type type, Boolean multiEdit) (at C:/clones/automation/Editor/Mono/CustomEditorAttributes.cs:45)
UnityEditor.AnnotationUtility:GetAnnotations()
UnityEditor.AnnotationWindow:SyncToState() (at C:/clones/automation/Editor/Mono/Annotation/AnnotationWindow.cs:229)
UnityEditor.AnnotationWindow:Init(Rect, Boolean) (at C:/clones/automation/Editor/Mono/Annotation/AnnotationWindow.cs:176)
UnityEditor.AnnotationWindow:ShowAtPosition(Rect, Boolean) (at C:/clones/automation/Editor/Mono/Annotation/AnnotationWindow.cs:159)
UnityEditor.GameView:DoToolbarGUI() (at C:/clones/automation/Editor/Mono/GameView/GameView.cs:479)
UnityEditor.GameView:OnGUI() (at C:/clones/automation/Editor/Mono/GameView/GameView.cs:569)
System.Reflection.MonoMethod:InternalInvoke(Object, Object[], Exception&)
System.Reflection.MonoMethod:Invoke(Object, BindingFlags, Binder, Object[], CultureInfo) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Reflection/MonoMethod.cs:222)
System.Reflection.MethodBase:Invoke(Object, Object[]) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Reflection/MethodBase.cs:115)
UnityEditor.HostView:Invoke(String, Object) (at C:/clones/automation/Editor/Mono/HostView.cs:188)
UnityEditor.HostView:Invoke(String) (at C:/clones/automation/Editor/Mono/HostView.cs:181)
UnityEditor.DockArea:OnGUI() (at C:/clones/automation/Editor/Mono/GUI/DockArea.cs:338)
"