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:126)
        at org.openide.explorer.propertysheet.CustomEditorAction.actionPerformed(CustomEditorAction.java:217)
        at org.openide.explorer.propertysheet.SheetTable.editCellAt(SheetTable.java:986)
        at javax.swing.plaf.basic.BasicTableUI$Handler.adjustFocusAndSelection(BasicTableUI.java:955)
        at javax.swing.plaf.basic.BasicTableUI$Handler.mouseReleased(BasicTableUI.java:1026)
        at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:232)
        at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:231)
        at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:231)
        at java.awt.Component.processMouseEvent(Component.java:5517)
        at javax.swing.JComponent.processMouseEvent(JComponent.java:3135)
        at org.openide.explorer.propertysheet.SheetTable.processMouseEvent(SheetTable.java:719)
        at java.awt.Component.processEvent(Component.java:5282)
        at java.awt.Container.processEvent(Container.java:1966)
        at java.awt.Component.dispatchEventImpl(Component.java:3984)
        at java.awt.Container.dispatchEventImpl(Container.java:2024)
        at java.awt.Component.dispatchEvent(Component.java:3819)
        at java.awt.LightweightDispatcher.retargetMouseEvent(LightweightDispatcher.java:4212)
        at java.awt.LightweightDispatcher.processMouseEvent(LightweightDispatcher.java:3892)
        at java.awt.LightweightDispatcher.dispatchEvent(LightweightDispatcher.java:3822)
        at java.awt.Container.dispatchEventImpl(Container.java:2010)
        at java.awt.Window.dispatchEventImpl(Window.java:1791)
        at java.awt.Component.dispatchEvent(Component.java:3819)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:463)
        at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:242)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:163)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:157)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:149)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:110)