java.lang.IllegalStateException: Node has been removed.
   at java.util.prefs.AbstractPreferences.get(AbstractPreferences.java:283)
   at org.netbeans.modules.projectapi.AuxiliaryConfigBasedPreferencesProvider$AuxiliaryConfigBasedPreferences.access$1901(AuxiliaryConfigBasedPreferencesProvider.java:447)
   at org.netbeans.modules.projectapi.AuxiliaryConfigBasedPreferencesProvider$AuxiliaryConfigBasedPreferences$2.run(AuxiliaryConfigBasedPreferencesProvider.java:676)
   at org.netbeans.modules.projectapi.AuxiliaryConfigBasedPreferencesProvider$AuxiliaryConfigBasedPreferences$2.run(AuxiliaryConfigBasedPreferencesProvider.java:674)
   at org.netbeans.modules.openide.util.DefaultMutexImplementation.readAccess(DefaultMutexImplementation.java:209)
   at org.openide.util.Mutex.readAccess(Mutex.java:250)
   at org.netbeans.modules.projectapi.nb.NbProjectManager$MutexImpl.readAccess(NbProjectManager.java:794)
   at org.openide.util.Mutex.readAccess(Mutex.java:218)
   at org.netbeans.modules.projectapi.AuxiliaryConfigBasedPreferencesProvider$AuxiliaryConfigBasedPreferences.get(AuxiliaryConfigBasedPreferencesProvider.java:674)
   at org.netbeans.modules.editor.indent.project.ProxyPreferences$PrefTracker.preferenceChange(ProxyPreferences.java:233)
   at sun.reflect.GeneratedMethodAccessor34.invoke(GeneratedMethodAccessor34.java:0)
   at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
   at java.lang.reflect.Method.invoke(Method.java:498)
   at org.openide.util.WeakListenerImpl$ProxyListener.invoke(WeakListenerImpl.java:487)
   at com.sun.proxy.$Proxy14.preferenceChange(.java:0)
   at java.util.prefs.AbstractPreferences$EventDispatchThread.run(AbstractPreferences.java:1496)