Run Advanced Bar Charts sample in Ensemble.
Repeat Actions > Delete Series until there is no more data.
Try to add several series with Actions > Add Series.
RESULT: Chart is animated but no bars appear.
Try to add single data item with Actions > Add Data Item.
RESULT: You get the following exception and the application stop responding:

java.lang.NullPointerException
at javafx.scene.chart.BarChart.getDataItem(BarChart.java:472)
at javafx.scene.chart.BarChart.layoutPlotChildren(BarChart.java:406)
at javafx.scene.chart.XYChart.layoutChartChildren(XYChart.java:687)
at javafx.scene.chart.Chart$1.layoutChildren(Chart.java:81)
at javafx.scene.Parent.layout(Parent.java:999)
at javafx.scene.Scene.layoutDirtyRoots(Scene.java:492)
at javafx.scene.Scene.doLayoutPass(Scene.java:465)
at javafx.scene.Scene.access$3000(Scene.java:152)
at javafx.scene.Scene$ScenePulseListener.pulse(Scene.java:1853)
at com.sun.javafx.tk.Toolkit.firePulse(Toolkit.java:357)
at com.sun.javafx.tk.quantum.QuantumToolkit.pulse(QuantumToolkit.java:458)
at com.sun.javafx.tk.quantum.QuantumToolkit$8.run(QuantumToolkit.java:325)
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$2$1.run(WinApplication.java:62)
at java.lang.Thread.run(Thread.java:722)