java.lang.NullPointerException
        at org.netbeans.modules.visualweb.propertyeditors.UrlPropertyPanel.generateTargetTree(UrlPropertyPanel.java:389)
        at org.netbeans.modules.visualweb.propertyeditors.UrlPropertyPanel.<init>(UrlPropertyPanel.java:134)
        at org.netbeans.modules.visualweb.propertyeditors.UrlPropertyEditor.getCustomEditor(UrlPropertyEditor.java:105)
        at org.netbeans.modules.visualweb.propertyeditors.binding.ValueBindingPropertyEditor.getCustomEditor(ValueBindingPropertyEditor.java:380)
        at org.openide.explorer.propertysheet.PropertyDialogManager.<init>(PropertyDialogManager.java:129)
        at org.openide.explorer.propertysheet.CustomEditorAction.actionPerformed(CustomEditorAction.java:217)
        at org.openide.explorer.propertysheet.SheetTable.processMouseEvent(SheetTable.java:710)
        at java.awt.Component.processEvent(Component.java:5803)
        at java.awt.Container.processEvent(Container.java:2058)
        at java.awt.Component.dispatchEventImpl(Component.java:4410)
        at java.awt.Container.dispatchEventImpl(Container.java:2116)
        at java.awt.Component.dispatchEvent(Component.java:4240)
        at java.awt.LightweightDispatcher.retargetMouseEvent(LightweightDispatcher.java:4322)
        at java.awt.LightweightDispatcher.processMouseEvent(LightweightDispatcher.java:3983)
        at java.awt.LightweightDispatcher.dispatchEvent(LightweightDispatcher.java:3916)
        at java.awt.Container.dispatchEventImpl(Container.java:2102)
        at java.awt.Window.dispatchEventImpl(Window.java:2429)
        at java.awt.Component.dispatchEvent(Component.java:4240)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
        at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:104)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:273)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:183)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:173)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:168)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:160)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:121)