java.lang.NullPointerException
        at org.netbeans.modules.css.editor.model.CssModel.<init>(CssModel.java:163)
        at org.netbeans.modules.css.editor.model.CssModel.get(CssModel.java:125)
        at org.netbeans.modules.css.editor.CssEditorSupport.cssTCActivated(CssEditorSupport.java:300)
        at org.netbeans.modules.css.visual.ui.preview.CSSTCController.previewableActivated(CSSTCController.java:153)
        at org.netbeans.modules.css.visual.ui.preview.CSSTCController.propertyChange(CSSTCController.java:97)
        at org.openide.util.WeakListenerImpl$PropertyChange.propertyChange(WeakListenerImpl.java:186)
        at java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:339)
        at java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:276)
        at org.netbeans.core.windows.RegistryImpl.doFirePropertyChange(RegistryImpl.java:314)
        at org.netbeans.core.windows.RegistryImpl.access$100(RegistryImpl.java:63)
        at org.netbeans.core.windows.RegistryImpl$1.run(RegistryImpl.java:166)
        at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:597)
        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)