If you start this application you will get a error.

package main;

import java.awt.Dimension;

import javax.swing.*;        

public class Swing {
    private static void createAndShowGUI() {

        JFrame frame = new JFrame("HelloWorldSwing");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JTextPane jTextpane = new JTextPane();
        frame.add(jTextpane);
        frame.setSize(new Dimension(600, 450));       
        frame.setVisible(true); 
    }

    public static void main(String[] args) {
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }
}

error:
jamvm main.Swing
Exception during event dispatch:
java.lang.AssertionError: No child views found where child views are expected. pos = 0, bias = forward
   at javax.swing.text.CompositeView.modelToView (CompositeView.java:234)
   at javax.swing.plaf.basic.BasicTextUI$RootView.modelToView (BasicTextUI.java:274)
   at javax.swing.plaf.basic.BasicTextUI.modelToView (BasicTextUI.java:942)
   at javax.swing.plaf.basic.BasicTextUI.modelToView (BasicTextUI.java:917)
   at javax.swing.text.JTextComponent.modelToView (JTextComponent.java:1548)
   at javax.swing.text.DefaultCaret.paint (DefaultCaret.java:581)
   at javax.swing.plaf.basic.BasicTextUI.paintSafely (BasicTextUI.java:802)
   at javax.swing.plaf.basic.BasicTextUI.paint (BasicTextUI.java:779)
   at javax.swing.plaf.ComponentUI.update (ComponentUI.java:192)
   at javax.swing.JComponent.paintComponent (JComponent.java:1627)
   at javax.swing.JComponent.paint (JComponent.java:1527)
   at javax.swing.JComponent.paintChildren (JComponent.java:1595)
   at javax.swing.JComponent.paint (JComponent.java:1529)
   at javax.swing.JComponent.paintChildren (JComponent.java:1595)
   at javax.swing.JComponent.paint (JComponent.java:1529)
   at javax.swing.JLayeredPane.paint (JLayeredPane.java:686)
   at javax.swing.JComponent.paintChildren (JComponent.java:1595)
   at javax.swing.JComponent.paint (JComponent.java:1529)
   at javax.swing.JComponent.paintDoubleBuffered (JComponent.java:1720)
   at javax.swing.JComponent.paint (JComponent.java:1522)
   at java.awt.Container$GfxPaintVisitor.visit (Container.java:1817)
   at java.awt.Container.visitChild (Container.java:1621)
   at java.awt.Container.visitChildren (Container.java:1583)
   at java.awt.Container.paint (Container.java:769)
   at javax.swing.JFrame.update (JFrame.java:282)
   at gnu.java.awt.peer.gtk.GtkComponentPeer.handleEvent (GtkComponentPeer.java:315)
   at java.awt.Component.dispatchEventImpl (Component.java:4846)
   at java.awt.Container.dispatchEventImpl (Container.java:1644)
   at java.awt.Window.dispatchEventImpl (Window.java:623)
   at java.awt.Component.dispatchEvent (Component.java:2341)
   at java.awt.EventQueue.dispatchEvent (EventQueue.java:474)
   at java.awt.EventDispatchThread.run (EventDispatchThread.java:75)