java.lang.NullPointerException
        at org.netbeans.modules.javafx.refactoring.impl.plugins.RenameRefactoringPlugin.variableClashes(RenameRefactoringPlugin.java:463)
        at org.netbeans.modules.javafx.refactoring.impl.plugins.RenameRefactoringPlugin.fastCheckParameters(RenameRefactoringPlugin.java:241)
        at org.netbeans.modules.javafx.refactoring.impl.plugins.JavaFXRefactoringPlugin$3.check(JavaFXRefactoringPlugin.java:79)
        at org.netbeans.modules.javafx.refactoring.impl.plugins.JavaFXRefactoringPlugin$4.run(JavaFXRefactoringPlugin.java:149)
        at org.netbeans.modules.javafx.refactoring.impl.plugins.JavaFXRefactoringPlugin$4.run(JavaFXRefactoringPlugin.java:147)
        at org.netbeans.modules.javafx.source.parsing.LegacyUserTask.run(LegacyUserTask.java:68)
        at org.netbeans.modules.parsing.api.ParserManager$UserTaskAction.run(ParserManager.java:129)
        at org.netbeans.modules.parsing.api.ParserManager$UserTaskAction.run(ParserManager.java:113)
Caused: org.netbeans.modules.parsing.spi.ParseException
        at org.netbeans.modules.parsing.impl.TaskProcessor.runUserTask(TaskProcessor.java:192)
        at org.netbeans.modules.parsing.api.ParserManager.parse(ParserManager.java:99)
        at org.netbeans.api.javafx.source.JavaFXSource.runUserActionTask(JavaFXSource.java:247)
        at org.netbeans.modules.javafx.refactoring.impl.plugins.JavaFXRefactoringPlugin.runCheck(JavaFXRefactoringPlugin.java:147)
        at org.netbeans.modules.javafx.refactoring.impl.plugins.JavaFXRefactoringPlugin.fastCheckParameters(JavaFXRefactoringPlugin.java:76)
        at org.netbeans.modules.refactoring.api.AbstractRefactoring.pluginsFastCheckParams(AbstractRefactoring.java:508)
        at org.netbeans.modules.refactoring.api.AbstractRefactoring.fastCheckParameters(AbstractRefactoring.java:262)
        at org.netbeans.modules.refactoring.api.AbstractRefactoring.checkParameters(AbstractRefactoring.java:239)
        at org.netbeans.modules.javafx.refactoring.impl.ui.RenameRefactoringUI.setParameters(RenameRefactoringUI.java:210)
        at org.netbeans.modules.refactoring.spi.impl.ParametersPanel$Prepare.run(ParametersPanel.java:787)
        at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:602)
        at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:1084)