How to reproduce:
1. Start JBDS.
2. Create a new JSF project.
3. Open index.jsp in VPE.
4. Close JBDS (not closing index.jsp page)
5. Delete the project's folder from your hard disc.
6. Start JBDS again.
ACTUAL RESULT: VPE shows text 'NULL' in the view of index.jsp
EXPECTED RESULT: the VPE view of index.jsp is empty.
7. Press 'Refresh' button in the VPE view.
ACTUAL RESULT: Message box 'Problem Occurred' appears.
EXPECTED RESULT: Nothing happens.

Also see stack trace:
org.eclipse.swt.SWTException: Failed to execute runnable (java.lang.NullPointerException)
at org.eclipse.swt.SWT.error(SWT.java:3777)
at org.eclipse.swt.SWT.error(SWT.java:3695)
at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:136)
at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.java:3800)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3425)
at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2382)
at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2346)
at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2198)
at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:493)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:288)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:488)
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:193)
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:386)
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:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:549)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:504)
at org.eclipse.equinox.launcher.Main.run(Main.java:1236)
at org.eclipse.equinox.launcher.Main.main(Main.java:1212)
Caused by: java.lang.NullPointerException
at org.jboss.tools.vpe.editor.VpeController.visualRefreshImpl(VpeController.java:1380)
at org.jboss.tools.vpe.editor.VpeController$4.runInUIThread(VpeController.java:1348)
at org.eclipse.ui.progress.UIJob$1.run(UIJob.java:94)
at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:35)
at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:133)
... 23 more