退出主应用程序时 JavaFX 出现异常

Question

当我退出 JavaFX 应用程序时，我（有时）在循环中有以下异常：

Exception in thread "JavaFX Application Thread" java.lang.NullPointerException
    at com.sun.javafx.tk.quantum.QuantumToolkit.isSupported(QuantumToolkit.java:1196)
    at com.sun.javafx.application.PlatformImpl.isSupportedImpl(PlatformImpl.java:809)
    at com.sun.javafx.application.PlatformImpl.isSupported(PlatformImpl.java:482)
    at javafx.application.Platform.isSupported(Platform.java:168)
    at com.sun.javafx.scene.input.PickResultChooser.processOffer(PickResultChooser.java:182)
    at com.sun.javafx.scene.input.PickResultChooser.offer(PickResultChooser.java:143)
    at javafx.scene.Node.impl_intersects(Node.java:4943)
    at javafx.scene.layout.Region.impl_pickNodeLocal(Region.java:2942)
    at javafx.scene.Node.impl_pickNode(Node.java:4912)
    at javafx.scene.layout.Region.impl_pickNodeLocal(Region.java:2936)
    at javafx.scene.Node.impl_pickNode(Node.java:4912)
    at javafx.scene.layout.Region.impl_pickNodeLocal(Region.java:2936)
    at javafx.scene.Node.impl_pickNode(Node.java:4912)
    at javafx.scene.layout.Region.impl_pickNodeLocal(Region.java:2936)
    at javafx.scene.Node.impl_pickNode(Node.java:4912)
    at javafx.scene.layout.Region.impl_pickNodeLocal(Region.java:2936)
    at javafx.scene.Node.impl_pickNode(Node.java:4912)
    at javafx.scene.Scene$MouseHandler.pickNode(Scene.java:3899)
    at javafx.scene.Scene$MouseHandler.access$1600(Scene.java:3485)
    at javafx.scene.Scene.pick(Scene.java:1942)
    at javafx.scene.Scene.access$6700(Scene.java:159)
    at javafx.scene.Scene$MouseHandler.process(Scene.java:3711)
    at javafx.scene.Scene$MouseHandler.access$1500(Scene.java:3485)
    at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1762)
    at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2494)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:394)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:295)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$2(GlassViewEventHandler.java:432)
    at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:410)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:431)
    at com.sun.glass.ui.View.handleMouseEvent(View.java:555)
    at com.sun.glass.ui.View.notifyMouse(View.java:937)
    at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at com.sun.glass.ui.win.WinApplication.lambda$null$4(WinApplication.java:187)
    at java.lang.Thread.run(Thread.java:748)

它不会以另一种方式影响我的应用程序，当我通过单击 Window 上的关闭按钮退出应用程序时似乎会发生这种情况。 当我退出时（并非总是如此），我有几个这样的堆栈（上次是 3，当然这不是一个无限循环）。

Note that I'm using Java 8, and I'm using a JavaFX Scene which is called from a non-JavaFX Thread (but using a Platform.runLater() code), and added as a JFXPanel in a Swing component. 我通过以下方式在我的主线程中创建它：

JFXPanel jfxPanel = new JFXPanel();
JFrame frame = new JFrame("GUI");
initGUI();
Container pane = frame.getContentPane();
pane.setLayout(new BorderLayout());
pane.add(jfxPanel, BorderLayout.CENTER);
frame.setVisible(true);

所有 JavaFX 代码在以下代码中执行：

private void initGUI() {
  Platform.runLater(new Runnable() {
     @Override
     public void run() {
        initFX();
     }
  });
}

当我使用该应用程序时，我绝对没有问题，只是当我退出时，我（有时）有这个异常。 我做错了什么？