Sample Test Case:

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.chart.NumberAxis;
import javafx.stage.Stage;

public class NumberAxisTest extends Application {
  public static void main(String[] args) throws Exception { launch(args); }
  public void start(Stage stage) throws Exception {
    stage.setScene(new Scene(new NumberAxis()));
    // this doesn't work either => stage.setScene(new Scene(NumberAxisBuilder.create().build()));
    stage.show();
  }
}

Sample Output:

Exception in Application start method
Exception in thread "main" java.lang.RuntimeException: Exception in Application start method
at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:378)
at com.sun.javafx.application.LauncherImpl.access$000(LauncherImpl.java:27)
at com.sun.javafx.application.LauncherImpl$1.run(LauncherImpl.java:97)
at java.lang.Thread.run(Thread.java:722)
Caused by: java.lang.NullPointerException
at javafx.scene.chart.Axis.impl_getPseudoClassState(Axis.java:1143)
at com.sun.javafx.css.StyleHelper.getPseudoClassState(StyleHelper.java:508)
at com.sun.javafx.css.StyleHelper.getAllPseudoClassStates(StyleHelper.java:520)
at com.sun.javafx.css.StyleHelper.transitionToState(StyleHelper.java:663)
at javafx.scene.Node.impl_processCSS(Node.java:6247)
at javafx.scene.Parent.impl_processCSS(Parent.java:965)
at javafx.scene.Node.processCSS(Node.java:6215)
at javafx.scene.Scene.doCSSPass(Scene.java:385)
at javafx.scene.Scene.preferredSize(Scene.java:1187)
at javafx.scene.Scene.impl_initPeer(Scene.java:593)
at javafx.stage.Window$13.invalidated(Window.java:686)
at javafx.beans.property.BooleanPropertyBase.markInvalid(BooleanPropertyBase.java:88)
at javafx.beans.property.BooleanPropertyBase.set(BooleanPropertyBase.java:122)
at javafx.stage.Window.setShowing(Window.java:744)
at javafx.stage.Window.show(Window.java:759)
at javafx.stage.Stage.show(Stage.java:129)
at tests.NumberAxisTest.start(NumberAxisTest.java:13)
at com.sun.javafx.application.LauncherImpl$5.run(LauncherImpl.java:298)
at com.sun.javafx.application.PlatformImpl$4.run(PlatformImpl.java:152)
at com.sun.javafx.application.PlatformImpl$3.run(PlatformImpl.java:119)
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)
... 1 more