org.netbeans.editor.GuardedException: Attempt to remove from guarded block at position 1?504.
   at org.netbeans.editor.GuardedDocument.preRemoveCheck(GuardedDocument.java:296)
   at org.netbeans.editor.BaseDocument.handleRemove(BaseDocument.java:973)
   at org.netbeans.editor.BaseDocument$FilterBypassImpl.remove(BaseDocument.java:2493)
   at javax.swing.text.DocumentFilter.remove(DocumentFilter.java:79)
   at org.openide.text.CloneableEditorSupport$DocFilter.remove(CloneableEditorSupport.java:2386)
   at org.netbeans.editor.BaseDocument.remove(BaseDocument.java:937)
   at org.netbeans.api.java.source.ModificationResult.processDocumentLocked(ModificationResult.java:433)
   at org.netbeans.api.java.source.ModificationResult.access$100(ModificationResult.java:97)
   at org.netbeans.api.java.source.ModificationResult$3.run(ModificationResult.java:401)
   at org.netbeans.editor.GuardedDocument.runAtomicAsUser(GuardedDocument.java:356)
   at org.openide.text.NbDocument.runAtomicAsUser(NbDocument.java:462)
Caused: java.io.IOException
   at org.netbeans.api.java.source.ModificationResult.processDocument(ModificationResult.java:421)
   at org.netbeans.api.java.source.ModificationResult.commit2(ModificationResult.java:363)
   at org.netbeans.api.java.source.ModificationResult.access$000(ModificationResult.java:97)
   at org.netbeans.api.java.source.ModificationResult$2.run(ModificationResult.java:265)
   at org.netbeans.editor.GuardedDocument.runAtomic(GuardedDocument.java:323)
   at org.openide.text.NbDocument.runAtomic(NbDocument.java:436)
   at org.netbeans.api.java.source.ModificationResult.commit(ModificationResult.java:262)
   at org.netbeans.api.java.source.ModificationResult.commit(ModificationResult.java:215)
   at org.netbeans.modules.refactoring.java.spi.JavaModificationResult.commit(JavaModificationResult.java:74)
Caused: java.lang.RuntimeException: java.io.IOException
   at org.netbeans.modules.refactoring.spi.RefactoringCommit.commit(RefactoringCommit.java:165)
   at org.netbeans.modules.refactoring.api.RefactoringSession.reallyDoRefactoring(RefactoringSession.java:166)
   at org.netbeans.modules.refactoring.api.RefactoringSession.access$100(RefactoringSession.java:79)
   at org.netbeans.modules.refactoring.api.RefactoringSession$1.run(RefactoringSession.java:122)
   at org.netbeans.modules.refactoring.api.RefactoringSession$1.run(RefactoringSession.java:120)
   at org.netbeans.modules.editor.lib.BeforeSaveTasks.runWithOnSaveTasksDisabled(BeforeSaveTasks.java:93)
   at org.netbeans.editor.Utilities.runWithOnSaveTasksDisabled(Utilities.java:1625)
   at org.netbeans.modules.refactoring.api.RefactoringSession.doRefactoring(RefactoringSession.java:120)
   at org.netbeans.modules.refactoring.spi.impl.RefactoringPanel$2.run(RefactoringPanel.java:556)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1423)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:2033)