java.lang.NullPointerException
        at org.netbeans.modules.viewmodel.TreeModelNode$TreeModelChildren.applyChildren(TreeModelNode.java:828)
        at org.netbeans.modules.viewmodel.TreeModelNode$TreeModelChildren.evaluateLazily(TreeModelNode.java:782)
        at org.netbeans.modules.viewmodel.TreeModelNode$LazyEvaluator.run(TreeModelNode.java:1179)
        at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:572)
        at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:997)
org.openide.ErrorManager$AnnException: msg
        at org.openide.ErrorManager$AnnException.findOrCreate(ErrorManager.java:861)
        at org.openide.ErrorManager$DelegatingErrorManager.annotate(ErrorManager.java:650)
        at org.openide.ErrorManager.annotate(ErrorManager.java:452)
        at org.netbeans.modules.viewmodel.TreeModelNode$TreeModelChildren.applyChildren(TreeModelNode.java:828)
        at org.netbeans.modules.viewmodel.TreeModelNode$TreeModelChildren.evaluateLazily(TreeModelNode.java:782)
        at org.netbeans.modules.viewmodel.TreeModelNode$LazyEvaluator.run(TreeModelNode.java:1179)
        at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:572)
        at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:997)