Application hangs sometimes during animation. No further rendering is made so this error breaks pulse loop.

java.lang.NullPointerException
at javafx.scene.Scene$ScenePulseListener.synchronizeSceneProperties(Scene.java:1798)
at javafx.scene.Scene$ScenePulseListener.pulse(Scene.java:1858)
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)