Cas Editor throws NPE when cleaning a document which is opened

The Cas Edtior throws an NPE when a document is "cleaned" with the clean action and the documen is open.

!ENTRY org.eclipse.jface 4 0 2009-12-01 18:02:09.672
!MESSAGE Unhandled event loop exception during blocked modal context.
!STACK 0
org.eclipse.swt.SWTException: Failed to execute runnable (java.lang.NullPointerException)
at org.eclipse.swt.SWT.error(SWT.java:3884)
at org.eclipse.swt.SWT.error(SWT.java:3799)
at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:137)
at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.java:3468)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3115)
at org.eclipse.jface.operation.ModalContext$ModalContextThread.block(ModalContext.java:173)
at org.eclipse.jface.operation.ModalContext.run(ModalContext.java:388)
at org.eclipse.jface.dialogs.ProgressMonitorDialog.run(ProgressMonitorDialog.java:507)
at org.eclipse.ui.internal.progress.ProgressMonitorJobsDialog.run(ProgressMonitorJobsDialog.java:275)
at org.eclipse.ui.internal.progress.ProgressManager.run(ProgressManager.java:1178)
at org.apache.uima.caseditor.ui.action.RunnableAction.run(RunnableAction.java:72)
at org.eclipse.jface.action.Action.runWithEvent(Action.java:498)
at org.eclipse.jface.action.ActionContributionItem.handleWidgetSelection(ActionContributionItem.java:584)
at org.eclipse.jface.action.ActionContributionItem.access$2(ActionContributionItem.java:501)
at org.eclipse.jface.action.ActionContributionItem$5.handleEvent(ActionContributionItem.java:411)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1176)
at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:3493)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3112)
at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2405)
at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2369)
at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2221)
at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:500)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:493)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:113)
at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:194)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:368)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:616)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:559)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:514)
at org.eclipse.equinox.launcher.Main.run(Main.java:1311)
Caused by: java.lang.NullPointerException
at org.apache.uima.caseditor.core.model.dotcorpus.DotCorpus.getAnnotation(DotCorpus.java:213)
at org.apache.uima.caseditor.core.model.DotCorpusElement.getAnnotation(DotCorpusElement.java:191)
at org.apache.uima.caseditor.editor.DefaultCasDocumentProvider.getAnnotationStyle(DefaultCasDocumentProvider.java:131)
at org.apache.uima.caseditor.editor.AnnotationEditor$AnnotationAccess.getLayer(AnnotationEditor.java:408)
at org.eclipse.jface.text.source.AnnotationPainter.getDecoration(AnnotationPainter.java:851)
at org.eclipse.jface.text.source.AnnotationPainter.catchupWithModel(AnnotationPainter.java:679)
at org.eclipse.jface.text.source.AnnotationPainter.updatePainting(AnnotationPainter.java:940)
at org.eclipse.jface.text.source.AnnotationPainter.paint(AnnotationPainter.java:1653)
at org.apache.uima.caseditor.editor.AnnotationEditor.syncAnnotations(AnnotationEditor.java:888)
at org.apache.uima.caseditor.editor.AnnotationEditor$DocumentListener.changed(AnnotationEditor.java:309)
at org.apache.uima.caseditor.editor.AbstractDocument.fireChanged(AbstractDocument.java:131)
at org.apache.uima.caseditor.editor.DocumentUimaImpl.changed(DocumentUimaImpl.java:156)
at org.apache.uima.caseditor.ui.action.DocumentActionRunnable$1.run(DocumentActionRunnable.java:132)
at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:35)
at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:134)
... 36 more