JSP Editor thrown a Null Pointer Exception

open a jsp-file ... eclipse shows a NPE ...

java.lang.NullPointerException
at org.jboss.tools.vpe.editor.mozilla.MozillaPreview.rebuildDom(MozillaPreview.java:444)
at org.jboss.tools.vpe.editor.VpeEditorPart.setVisualMode(VpeEditorPart.java:373)
at org.jboss.tools.jst.jsp.jspeditor.JSPMultiPageEditor.pageChange(JSPMultiPageEditor.java:223)
at org.jboss.tools.jst.jsp.jspeditor.JSPMultiPageEditor.createPages(JSPMultiPageEditor.java:385)
at org.jboss.tools.jst.jsp.jspeditor.JSPMultiPageEditorPart.createPartControl(JSPMultiPageEditorPart.java:124)
at org.eclipse.ui.internal.EditorReference.createPartHelper(EditorReference.java:661)
at org.eclipse.ui.internal.EditorReference.createPart(EditorReference.java:426)
at org.eclipse.ui.internal.WorkbenchPartReference.getPart(WorkbenchPartReference.java:592)
at org.eclipse.ui.internal.EditorReference.getEditor(EditorReference.java:263)
at org.eclipse.ui.internal.WorkbenchPage.busyOpenEditorBatched(WorkbenchPage.java:2739)
at org.eclipse.ui.internal.WorkbenchPage.busyOpenEditor(WorkbenchPage.java:2651)
at org.eclipse.ui.internal.WorkbenchPage.access$13(WorkbenchPage.java:2643)
at org.eclipse.ui.internal.WorkbenchPage$10.run(WorkbenchPage.java:2595)
at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:67)
at org.eclipse.ui.internal.WorkbenchPage.openEditor(WorkbenchPage.java:2590)
at org.eclipse.ui.internal.WorkbenchPage.openEditor(WorkbenchPage.java:2574)
at org.eclipse.ui.actions.OpenWithMenu.openEditor(OpenWithMenu.java:340)
at org.eclipse.ui.actions.OpenWithMenu.access$0(OpenWithMenu.java:328)
at org.eclipse.ui.actions.OpenWithMenu$2.handleEvent(OpenWithMenu.java:190)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:66)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:938)
at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:3682)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3293)
at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2389)
at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2353)
at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2219)
at org.eclipse.ui.internal.Workbench$4.run(Workbench.java:466)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:289)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:461)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:106)
at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:169)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:106)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:76)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:363)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:176)
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:508)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:447)
at org.eclipse.equinox.launcher.Main.run(Main.java:1173)