java.lang.NullPointerException: Cannot find previous mode named 'navigator' at org.netbeans.core.windows.PersistenceHandler.initPreviousModes(PersistenceHandler.java:337) at org.netbeans.core.windows.PersistenceHandler.load(PersistenceHandler.java:188) at org.netbeans.core.windows.WindowSystemImpl.load(WindowSystemImpl.java:47) at org.netbeans.core.NonGui$3.run(NonGui.java:183) at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209) at java.awt.EventQueue.dispatchEvent(EventQueue.java:597) 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)