java.lang.NullPointerException
        at org.netbeans.api.java.source.support.CaretAwareJavaSourceTaskFactory$ChangeListenerImpl.stateChanged(CaretAwareJavaSourceTaskFactory.java:147)
        at org.netbeans.api.java.source.support.OpenedEditors.fireChangeEvent(OpenedEditors.java:116)
        at org.netbeans.api.java.source.support.OpenedEditors.stateChanged(OpenedEditors.java:172)
        at org.netbeans.api.java.source.support.OpenedEditors$1.propertyChange(OpenedEditors.java:86)
        at java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:333)
        at org.netbeans.api.editor.EditorRegistry.fireEvents(EditorRegistry.java:478)
        at org.netbeans.api.editor.EditorRegistry.focusGained(EditorRegistry.java:295)
        at org.netbeans.api.editor.EditorRegistry$FocusL.focusGained(EditorRegistry.java:577)
        at java.awt.AWTEventMulticaster.focusGained(AWTEventMulticaster.java:162)
        at java.awt.Component.processFocusEvent(Component.java:5491)
        at java.awt.Component.processEvent(Component.java:5358)
        at java.awt.Container.processEvent(Container.java:2010)
        at java.awt.Component.dispatchEventImpl(Component.java:4068)
        at java.awt.Container.dispatchEventImpl(Container.java:2068)
        at java.awt.Component.dispatchEvent(Component.java:3903)
        at java.awt.KeyboardFocusManager.redispatchEvent(KeyboardFocusManager.java:1826)
        at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(DefaultKeyboardFocusManager.java:849)
        at java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:489)
        at java.awt.Component.dispatchEventImpl(Component.java:3941)
        at java.awt.Container.dispatchEventImpl(Container.java:2068)
        at java.awt.Component.dispatchEvent(Component.java:3903)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:463)
        at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:104)
        at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:269)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:190)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:184)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:176)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:110)