If you create a line chart with option LineChart.setCreateSymbols(false) set to false, then invoking method LineChart.getData().clear() throws a NullPointer exception. This works fine if LineChart.setCreateSymbols(true) is set.

Suggestion for a work around?

Here is the stack trace:
java.lang.NullPointerException
at javafx.scene.chart.LineChart.seriesRemoved(LineChart.java:377)
at javafx.scene.chart.XYChart$2.onChanged(XYChart.java:99)
at com.sun.javafx.collections.ListListenerHelper$SingleChange.fireValueChangedEvent(ListListenerHelper.java:134)
at com.sun.javafx.collections.ListListenerHelper.fireValueChangedEvent(ListListenerHelper.java:48)
at com.sun.javafx.collections.ObservableListWrapper.callObservers(ObservableListWrapper.java:97)
at com.sun.javafx.collections.ObservableListWrapper.clear(ObservableListWrapper.java:184)
at com.sas.analytics.demo.LineChartSample$2.handle(LineChartSample.java:43)
at com.sas.analytics.demo.LineChartSample$2.handle(LineChartSample.java:1)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:69)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:217)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:170)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:38)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:37)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:53)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:28)
at javafx.event.Event.fireEvent(Event.java:171)
at javafx.scene.Node.fireEvent(Node.java:6863)
at javafx.scene.control.Button.fire(Button.java:179)
at com.sun.javafx.scene.control.behavior.ButtonBehavior.mouseReleased(ButtonBehavior.java:193)
at com.sun.javafx.scene.control.skin.SkinBase$4.handle(SkinBase.java:336)
at com.sun.javafx.scene.control.skin.SkinBase$4.handle(SkinBase.java:329)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:64)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:217)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:170)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:38)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:37)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:53)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:33)
at javafx.event.Event.fireEvent(Event.java:171)
at javafx.scene.Scene$MouseHandler.process(Scene.java:3328)
at javafx.scene.Scene$MouseHandler.process(Scene.java:3168)
at javafx.scene.Scene$MouseHandler.access$1900(Scene.java:3123)
at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1563)
at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2265)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:250)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:173)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:292)
at com.sun.glass.ui.View.handleMouseEvent(View.java:528)
at com.sun.glass.ui.View.notifyMouse(View.java:922)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.access$100(WinApplication.java:29)
at com.sun.glass.ui.win.WinApplication$3$1.run(WinApplication.java:73)
at java.lang.Thread.run(Thread.java:722)

Here is a program that uses the line chart sample from the JavaFX tutorial page that replicates this problem:
public class LineChartSample extends Application
{
private static String[] MONTHS = { "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" };

private LineChart<String,Number> lineChart;

    @Override public void start(Stage stage)
    {
        // Create series button
        Button createButton = new Button("Add Series");
        createButton.setOnAction(new EventHandler<ActionEvent>()
        {
@Override
public void handle(ActionEvent arg0)
{
addSeries();
}
        });

        // Remove all series button
        Button removeAllButton = new Button("Remove All");
        removeAllButton.setOnAction(new EventHandler<ActionEvent>()
        {
@Override
public void handle(ActionEvent arg0)
{
lineChart.getData().clear();
}
        });
        
        // Button box
        HBox buttonBox = new HBox(4);
        buttonBox.getChildren().addAll(createButton, removeAllButton);

        // Line chart
        final CategoryAxis xAxis = new CategoryAxis();
        final NumberAxis yAxis = new NumberAxis();
        xAxis.setLabel("Month");
        lineChart = new LineChart<String,Number>(xAxis,yAxis);
        lineChart.setTitle("Stock Monitoring, 2010");
        lineChart.setCreateSymbols(false);
        addSeries();
        
        // Content box
        VBox contentBox = new VBox();
        VBox.setVgrow(contentBox, Priority.ALWAYS);
        contentBox.getChildren().addAll(buttonBox, lineChart);
     
        stage.setTitle("Line Chart Sample");
        Scene scene = new Scene(contentBox, 800, 600);
        stage.setScene(scene);
        stage.show();
    }
    
    private void addSeries()
    {
        XYChart.Series series = new XYChart.Series();
        series.setName("Series " + (lineChart.getData().size() + 1));
        
        for (String month : MONTHS)
        {
         series.getData().add(new XYChart.Data(month, Math.random() * 100));
        }
        
        lineChart.getData().add(series);
    }
        
    public static void main(String[] args)
    {
        launch(args);
    }

}

Thanks.
Stefan