title: NullPointerException when using Slider.setShowTickLabels method in JavaFX
body: <p><code>NullPointerException</code> when using <code>Slider.setShowTickLabels</code> method.</p>
  <p>I'm using <strong>JavaFX SDK 17.0.1</strong> and <strong>JDK 11.0.13.8</strong></p>
  <p>Windows 10</p>
  <pre><code>public void start(Stage window) {
      BorderPane pane = new BorderPane();
  
      Slider slider = new Slider(0, 100, 0);
      slider.setShowTickMarks(true);
  //        slider.setShowTickLabels(true);
  
      pane.setCenter(slider);
  
      Scene scene = new Scene(pane);
      window.setScene(scene);
      window.setTitle(&quot;Application&quot;);
      window.show();
  }
  </code></pre>
  <p>Output when <code>slider.setShowTickLabels(true)</code> is commented out.</p>
  <p><img src="https://i.stack.imgur.com/qF7Xz.png" alt="" /></p>
  <p>Getting an exception when including the same method.</p>
  <pre><code>java.lang.NullPointerException
      at javafx.graphics/com.sun.javafx.font.directwrite.DWGlyph.createBitmap(DWGlyph.java:287)
      at javafx.graphics/com.sun.javafx.font.directwrite.DWGlyph.getCachedBitmap(DWGlyph.java:273)
      at javafx.graphics/com.sun.javafx.font.directwrite.DWGlyph.getD2DMask(DWGlyph.java:167)
      at javafx.graphics/com.sun.javafx.font.directwrite.DWGlyph.getPixelData(DWGlyph.java:352)
      at javafx.graphics/com.sun.prism.impl.GlyphCache.getCachedGlyph(GlyphCache.java:258)
      at javafx.graphics/com.sun.prism.impl.GlyphCache.render(GlyphCache.java:148)
      at javafx.graphics/com.sun.prism.impl.ps.BaseShaderGraphics.drawString(BaseShaderGraphics.java:2101)
      at javafx.graphics/com.sun.javafx.sg.prism.NGText.renderText(NGText.java:312)
      at javafx.graphics/com.sun.javafx.sg.prism.NGText.renderContent2D(NGText.java:270)
      at javafx.graphics/com.sun.javafx.sg.prism.NGShape.renderContent(NGShape.java:261)
      at javafx.graphics/com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:2072)
      at javafx.graphics/com.sun.javafx.sg.prism.NGNode.render(NGNode.java:1964)
      at javafx.graphics/com.sun.javafx.sg.prism.NGGroup.renderContent(NGGroup.java:270)
      at javafx.graphics/com.sun.javafx.sg.prism.NGRegion.renderContent(NGRegion.java:578)
      at javafx.graphics/com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:2072)
      at javafx.graphics/com.sun.javafx.sg.prism.NGNode.render(NGNode.java:1964)
      at javafx.graphics/com.sun.javafx.sg.prism.NGGroup.renderContent(NGGroup.java:270)
      at javafx.graphics/com.sun.javafx.sg.prism.NGRegion.renderContent(NGRegion.java:578)
      at javafx.graphics/com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:2072)
      at javafx.graphics/com.sun.javafx.sg.prism.NGNode.render(NGNode.java:1964)
      at javafx.graphics/com.sun.javafx.sg.prism.NGGroup.renderContent(NGGroup.java:270)
      at javafx.graphics/com.sun.javafx.sg.prism.NGRegion.renderContent(NGRegion.java:578)
      at javafx.graphics/com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:2072)
      at javafx.graphics/com.sun.javafx.sg.prism.NGNode.render(NGNode.java:1964)
      at javafx.graphics/com.sun.javafx.tk.quantum.ViewPainter.doPaint(ViewPainter.java:479)
      at javafx.graphics/com.sun.javafx.tk.quantum.ViewPainter.paintImpl(ViewPainter.java:328)
      at javafx.graphics/com.sun.javafx.tk.quantum.PresentingPainter.run(PresentingPainter.java:91)
      at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
      at java.base/java.util.concurrent.FutureTask.runAndReset(FutureTask.java:305)
      at javafx.graphics/com.sun.javafx.tk.RenderJob.run(RenderJob.java:58)
      at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
      at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
      at javafx.graphics/com.sun.javafx.tk.quantum.QuantumRenderer$PipelineRunnable.run(QuantumRenderer.java:125)
      at java.base/java.lang.Thread.run(Thread.java:829)
  </code></pre>
  <p>Any help would be greatly appreciated, thanks.</p>