java.lang.NullPointerException
        at org.netbeans.spi.viewmodel.Models$DelegatingTreeModel.getChildrenCount(Models.java:1367)
        at org.netbeans.modules.debugger.jpda.ui.models.VariablesTreeModelFilterSI.getChildrenCount(VariablesTreeModelFilterSI.java:199)
        at org.netbeans.spi.viewmodel.Models$CompoundTreeModel.getChildrenCount(Models.java:754)
        at org.netbeans.modules.debugger.jpda.ui.FixedWatchesManager.getChildrenCount(FixedWatchesManager.java:225)
        at org.netbeans.spi.viewmodel.Models$CompoundTreeModel.getChildrenCount(Models.java:754)
        at org.netbeans.modules.debugger.jpda.ui.models.VariablesTreeModelFilter.getChildrenCount(VariablesTreeModelFilter.java:243)
        at org.netbeans.spi.viewmodel.Models$CompoundTreeModel.getChildrenCount(Models.java:754)
        at org.netbeans.modules.javafx.debugger.watchesfiltering.JavaFXWatchesTreeModelFilter.getChildrenCount(JavaFXWatchesTreeModelFilter.java:108)
        at org.netbeans.spi.viewmodel.Models$CompoundTreeModel.getChildrenCount(Models.java:754)
        at org.netbeans.spi.viewmodel.Models$CompoundModel.getChildrenCount(Models.java:3339)
        at org.netbeans.modules.viewmodel.TreeModelNode$TreeModelChildren.getModelChildren(TreeModelNode.java:938)
        at org.netbeans.modules.viewmodel.TreeModelNode$TreeModelChildren.evaluateLazily(TreeModelNode.java:900)
        at org.netbeans.modules.viewmodel.TreeModelNode$LazyEvaluator.run(TreeModelNode.java:1387)
        at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:602)
        at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:1070)