Primefaces ^ bar encode : java.lang.NullPointerException
	at org.primefaces.component.chart.ChartRenderer.encodeScript(ChartRenderer.java:95)
	at org.primefaces.component.chart.ChartRenderer.encodeEnd(ChartRenderer.java:68)
	at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:875)
	at com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.encodeRecursive(HtmlBasicRenderer.java:312)