java.lang.NullPointerException
	at org.netbeans.modules.uml.drawingarea.dataobject.DiagramDataObject$Save.save(DiagramDataObject.java:131)
	at org.netbeans.modules.uml.drawingarea.DiagramTopComponent.save(DiagramTopComponent.java:573)
	at org.netbeans.modules.uml.drawingarea.DiagramTopComponent.canClose(DiagramTopComponent.java:509)
	at org.openide.windows.TopComponent.close(TopComponent.java:418)
	at org.openide.windows.TopComponent.close(TopComponent.java:405)
[catch] at org.netbeans.modules.uml.drawingarea.UMLDiagramManager$3.run(UMLDiagramManager.java:334)
	at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
	at java.awt.EventQueue.dispatchEvent(EventQueue.java:597)
	at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:273)
	at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:183)
	at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:173)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:168)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:160)
	at java.awt.EventDispatchThread.run(EventDispatchThread.java:121)