i got a exception not from my code:

java.lang.NullPointerException
	at com.sun.t2k.T2KFontFactory.getFontResourceByFileName(Unknown Source)
	at com.sun.t2k.T2KFontFactory.getFontResource(Unknown Source)
	at com.sun.t2k.LogicalFont.getSlotResource(Unknown Source)
	at com.sun.t2k.CompositeGlyphMapper.getSlotMapper(Unknown Source)
	at com.sun.t2k.CompositeGlyphMapper.convertToGlyph(Unknown Source)
	at com.sun.t2k.CompositeGlyphMapper.getGlyphCode(Unknown Source)
	at com.sun.t2k.CharToGlyphMapper.charToGlyph(Unknown Source)
	at com.sun.javafx.sg.prism.NGText.getTabExpandedAdvance(Unknown Source)
	at com.sun.javafx.sg.prism.NGText.buildTextLines(Unknown Source)
	at com.sun.javafx.sg.prism.NGText.updateText(Unknown Source)
	at com.sun.javafx.sg.prism.NGText.computeBoundsLogical(Unknown Source)
	at com.sun.javafx.sg.prism.NGText.computeLayoutBounds(Unknown Source)
	at com.sun.javafx.tk.quantum.PrismTextHelper.computeLayoutBounds(Unknown Source)
	at javafx.scene.text.Text.impl_computeLayoutBoundsInt(Unknown Source)
	at javafx.scene.text.Text.impl_computeLayoutBounds(Unknown Source)
	at javafx.scene.Node$15.computeBounds(Unknown Source)
	at javafx.scene.Node$LazyBoundsProperty.get(Unknown Source)
	at javafx.scene.Node$LazyBoundsProperty.get(Unknown Source)
	at javafx.scene.Node.getLayoutBounds(Unknown Source)
	at javafx.scene.chart.PieChart.resolveCollision(Unknown Source)
	at javafx.scene.chart.PieChart.layoutChartChildren(Unknown Source)
	at javafx.scene.chart.Chart$1.layoutChildren(Unknown Source)
	at javafx.scene.Parent.layout(Unknown Source)
	at javafx.scene.Parent.layout(Unknown Source)
	at javafx.scene.Parent.layout(Unknown Source)
	at javafx.scene.Parent.layout(Unknown Source)
	at javafx.scene.Parent.layout(Unknown Source)
	at javafx.scene.Parent.layout(Unknown Source)
	at javafx.scene.Parent.layout(Unknown Source)
	at javafx.scene.Parent.layout(Unknown Source)
	at javafx.scene.Parent.layout(Unknown Source)
	at javafx.scene.Parent.layout(Unknown Source)
	at javafx.scene.Parent.layout(Unknown Source)
	at javafx.scene.Scene.layoutDirtyRoots(Unknown Source)
	at javafx.scene.Scene.doLayoutPass(Unknown Source)
	at javafx.scene.Scene.access$3000(Unknown Source)
	at javafx.scene.Scene$ScenePulseListener.pulse(Unknown Source)
	at com.sun.javafx.tk.Toolkit.firePulse(Unknown Source)
	at com.sun.javafx.tk.quantum.QuantumToolkit.pulse(Unknown Source)
	at com.sun.javafx.tk.quantum.QuantumToolkit$8.run(Unknown Source)
	at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
	at com.sun.glass.ui.win.WinApplication.access$100(Unknown Source)
	at com.sun.glass.ui.win.WinApplication$2$1.run(Unknown Source)
	at java.lang.Thread.run(Unknown Source)