Following 'The Sigasi HDT Tutorial', I've encountered the following error:

"A fatal error occurred while performing the refactoring
An unexpected exception occurred while creating a change object. See the error log for morre details."

Here are the steps to reproduce the bug:

1. Run the tutorial until you reach HDT Tutorial > Extend the design > Adding a port.
2. In the outline view, right click the clock generator entity and select Add port.
3. In the pop-up window, fill in the port name clock2 and a datatype std_logic for the new port.
4. Use Preview to confirm that a new port will be added to the clock generator.
5. Click Back
6. Click Preview again
7. The user is presented with an error:
A fatal error occurred while performing the refactoring
An unexpected exception occurred while creating a change object. See the error log for morre details.

I have included the error log below. Hope it helps!

Best regards,

Ricardo.

=====================================================================
!ENTRY org.eclipse.ltk.ui.refactoring 4 10000 2010-09-11 12:01:32.258
!MESSAGE Internal Error
!STACK 0
java.lang.reflect.InvocationTargetException
at org.eclipse.jface.operation.ModalContext.run(ModalContext.java:421)
at org.eclipse.ltk.internal.ui.refactoring.RefactoringWizardDialog2.run(RefactoringWizardDialog2.java:330)
at org.eclipse.ltk.ui.refactoring.RefactoringWizard.createChange(RefactoringWizard.java:599)
at org.eclipse.ltk.ui.refactoring.RefactoringWizard.computeUserInputSuccessorPage(RefactoringWizard.java:438)
at org.eclipse.ltk.ui.refactoring.UserInputWizardPage.computeSuccessorPage(UserInputWizardPage.java:74)
at org.eclipse.ltk.ui.refactoring.UserInputWizardPage.getNextPage(UserInputWizardPage.java:114)
at org.eclipse.ltk.internal.ui.refactoring.RefactoringWizardDialog2.nextOrPreviewPressed(RefactoringWizardDialog2.java:496)
at org.eclipse.ltk.internal.ui.refactoring.RefactoringWizardDialog2.access$2(RefactoringWizardDialog2.java:493)
at org.eclipse.ltk.internal.ui.refactoring.RefactoringWizardDialog2$1.widgetSelected(RefactoringWizardDialog2.java:692)
at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:234)
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.jface.window.Window.runEventLoop(Window.java:825)
at org.eclipse.jface.window.Window.open(Window.java:801)
at org.eclipse.ltk.ui.refactoring.RefactoringWizardOpenOperation$1.run(RefactoringWizardOpenOperation.java:180)
at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:70)
at org.eclipse.ltk.ui.refactoring.RefactoringWizardOpenOperation.run(RefactoringWizardOpenOperation.java:192)
at org.eclipse.ltk.ui.refactoring.RefactoringWizardOpenOperation.run(RefactoringWizardOpenOperation.java:115)
at com.sigasi.veditor.ui.AddGenericOrPortAction.run(Unknown Source)
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: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:2629)
at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2593)
at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2427)
at org.eclipse.ui.internal.Workbench$7.run(Workbench.java:670)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:663)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:115)
at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:369)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:619)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:574)
at org.eclipse.equinox.launcher.Main.run(Main.java:1407)
Caused by: org.eclipse.core.runtime.AssertionFailedException: assertion failed:
at org.eclipse.core.runtime.Assert.isTrue(Assert.java:110)
at org.eclipse.core.runtime.Assert.isTrue(Assert.java:96)
at org.eclipse.ltk.core.refactoring.CompositeChange.add(CompositeChange.java:111)
at com.sigasi.hdt.refactoring.AddGenericOrPortRefactoring.createChange(Unknown Source)
at org.eclipse.ltk.core.refactoring.CreateChangeOperation.run(CreateChangeOperation.java:124)
at org.eclipse.core.internal.resources.Workspace.run(Workspace.java:1975)
at org.eclipse.ltk.internal.ui.refactoring.WorkbenchRunnableAdapter.run(WorkbenchRunnableAdapter.java:87)
at org.eclipse.jface.operation.ModalContext$ModalContextThread.run(ModalContext.java:121)
Root exception:
org.eclipse.core.runtime.AssertionFailedException: assertion failed:
at org.eclipse.core.runtime.Assert.isTrue(Assert.java:110)
at org.eclipse.core.runtime.Assert.isTrue(Assert.java:96)
at org.eclipse.ltk.core.refactoring.CompositeChange.add(CompositeChange.java:111)
at com.sigasi.hdt.refactoring.AddGenericOrPortRefactoring.createChange(Unknown Source)
at org.eclipse.ltk.core.refactoring.CreateChangeOperation.run(CreateChangeOperation.java:124)
at org.eclipse.core.internal.resources.Workspace.run(Workspace.java:1975)
at org.eclipse.ltk.internal.ui.refactoring.WorkbenchRunnableAdapter.run(WorkbenchRunnableAdapter.java:87)
at org.eclipse.jface.operation.ModalContext$ModalContextThread.run(ModalContext.java:121)