Null pointer exception during clip operation

[LogicAndTrick]

http://bugs.sledge-editor.com/Bug/View/11

Object reference not set to an instance of an object. (System.NullReferenceException)
   at Sledge.Editor.Actions.MapObjects.Operations.Clip.Perform(Document document)
   at Sledge.Editor.Documents.Document.PerformAction(String name, IAction action)
Action exception: Perform Clip (Sledge.Editor.Actions.MapObjects.Operations.Clip)
    Sledge.Editor.Documents.Document.PerformAction
    Sledge.Editor.Tools.ClipTool.PerformClip
    Sledge.Editor.Tools.ClipTool.KeyPress

This one happened when clipping a torus in half. Needs investigation.