To reproduce click 'Permute' twice and you will get:

Exception in thread "JavaFX Application Thread" java.lang.NullPointerException
at javafx.scene.chart.XYChart$Series$1.onChanged(XYChart.java:1507)
at com.sun.javafx.collections.ListListenerHelper$SingleChange.fireValueChangedEvent(ListListenerHelper.java:158)
at com.sun.javafx.collections.ListListenerHelper.fireValueChangedEvent(ListListenerHelper.java:72)
at javafx.collections.ObservableListBase.fireChange(ObservableListBase.java:233)
at javafx.collections.ListChangeBuilder.commit(ListChangeBuilder.java:482)
at javafx.collections.ListChangeBuilder.endChange(ListChangeBuilder.java:541)
at javafx.collections.ObservableListBase.endChange(ObservableListBase.java:205)
at javafx.collections.ModifiableObservableListBase.add(ModifiableObservableListBase.java:155)
at java.util.AbstractList.add(AbstractList.java:108)
...


import javafx.application.Application;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.chart.LineChart;
import javafx.scene.chart.NumberAxis;
import javafx.scene.chart.XYChart;
import javafx.scene.control.Button;
import javafx.scene.layout.HBox;
import javafx.stage.Stage;

public class TestApp extends Application {


    @Override
    public void start(Stage stage) throws Exception {

        NumberAxis xAxis = new NumberAxis();
        NumberAxis yAxis = new NumberAxis();

        final LineChart<Number, Number> lineChart = new LineChart<Number, Number>(xAxis, yAxis);

        XYChart.Series<Number, Number> series = new XYChart.Series<Number, Number>();
        series.setData(list);

        lineChart.getData().add(series);

        Button permuteList = new Button("Permute list");
        permuteList.setOnAction(new EventHandler<ActionEvent>() {
            @Override
            public void handle(ActionEvent actionEvent) {
                list.add(list.remove(0));
            }
        });

        Scene scene = new Scene(new HBox(4, lineChart, permuteList));
        stage.setScene(scene);
        stage.show();
    }

    private ObservableList<XYChart.Data<Number, Number>> list
            = FXCollections.observableArrayList(
                new XYChart.Data<Number, Number>(4, 1),
                new XYChart.Data<Number, Number>(1, 1),
                new XYChart.Data<Number, Number>(2, 2),
                new XYChart.Data<Number, Number>(3, 3));

    public static void main(String[] args) {
        launch(args);
    }
}