#18 NullPointerException in CssMergeViewer.java:119

[Anonymous]

I'm using Eclipse Helios (let me know if you need specifics) and I'm getting this error:

java.lang.NullPointerException
at net.sourceforge.csseditor.internal.compare.CssMergeViewer.getDocumentPartitioner(CssMergeViewer.java:119)
at org.eclipse.compare.contentmergeviewer.TextMergeViewer.canHaveSharedDocument(TextMergeViewer.java:2664)
at org.eclipse.compare.contentmergeviewer.TextMergeViewer.getElementDocument(TextMergeViewer.java:2655)
at org.eclipse.compare.contentmergeviewer.TextMergeViewer.getDocument(TextMergeViewer.java:2674)
at org.eclipse.compare.contentmergeviewer.TextMergeViewer.removeFromDocumentManager(TextMergeViewer.java:2726)
at org.eclipse.compare.contentmergeviewer.TextMergeViewer.handleDispose(TextMergeViewer.java:1811)
at net.sourceforge.csseditor.internal.compare.CssMergeViewer.handleDispose(CssMergeViewer.java:141)
at org.eclipse.jface.viewers.ContentViewer$2.widgetDisposed(ContentViewer.java:214)
at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:123)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1053)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1077)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1058)
at org.eclipse.swt.widgets.Widget.release(Widget.java:808)
at org.eclipse.swt.widgets.Composite.releaseChildren(Composite.java:872)
at org.eclipse.swt.widgets.Widget.release(Widget.java:811)
at org.eclipse.swt.widgets.Composite.releaseChildren(Composite.java:872)
at org.eclipse.swt.widgets.Widget.release(Widget.java:811)
at org.eclipse.swt.widgets.Composite.releaseChildren(Composite.java:872)
at org.eclipse.swt.widgets.Widget.release(Widget.java:811)
at org.eclipse.swt.widgets.Composite.releaseChildren(Composite.java:872)
at org.eclipse.swt.widgets.Widget.release(Widget.java:811)
at org.eclipse.swt.widgets.Composite.releaseChildren(Composite.java:872)
at org.eclipse.swt.widgets.Widget.release(Widget.java:811)
at org.eclipse.swt.widgets.Widget.dispose(Widget.java:446)
at org.eclipse.ui.internal.PartPane.dispose(PartPane.java:180)
at org.eclipse.ui.internal.WorkbenchPartReference.dispose(WorkbenchPartReference.java:681)
at org.eclipse.ui.internal.WorkbenchPage.disposePart(WorkbenchPage.java:1721)
at org.eclipse.ui.internal.WorkbenchPage.handleDeferredEvents(WorkbenchPage.java:1426)
at org.eclipse.ui.internal.WorkbenchPage.deferUpdates(WorkbenchPage.java:1410)
at org.eclipse.ui.internal.WorkbenchPage.closeEditors(WorkbenchPage.java:1384)
at org.eclipse.ui.internal.WorkbenchPage.closeEditor(WorkbenchPage.java:1439)
at org.eclipse.ui.internal.EditorPane.doHide(EditorPane.java:61)
at org.eclipse.ui.internal.PartStack.close(PartStack.java:541)
at org.eclipse.ui.internal.EditorStack.close(EditorStack.java:206)
at org.eclipse.ui.internal.PartStack$1.close(PartStack.java:120)
at org.eclipse.ui.internal.presentations.util.TabbedStackPresentation$1.handleEvent(TabbedStackPresentation.java:83)
at org.eclipse.ui.internal.presentations.util.AbstractTabFolder.fireEvent(AbstractTabFolder.java:269)
at org.eclipse.ui.internal.presentations.util.AbstractTabFolder.fireEvent(AbstractTabFolder.java:278)
at org.eclipse.ui.internal.presentations.defaultpresentation.DefaultTabFolder.access$1(DefaultTabFolder.java:1)
at org.eclipse.ui.internal.presentations.defaultpresentation.DefaultTabFolder$1.closeButtonPressed(DefaultTabFolder.java:71)
at org.eclipse.ui.internal.presentations.PaneFolder.notifyCloseListeners(PaneFolder.java:631)
at org.eclipse.ui.internal.presentations.PaneFolder$4.mouseUp(PaneFolder.java:230)
at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:213)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1053)
at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:4066)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3657)
at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2640)
at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2604)
at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2438)
at org.eclipse.ui.internal.Workbench$7.run(Workbench.java:671)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:664)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:115)
at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196)
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:369)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:620)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:575)
at org.eclipse.equinox.launcher.Main.run(Main.java:1408)

I've had a glance at the source and it seems this is happening because of an illegal state.