Bug in code from Java Tutorial or is it just me?

I copied and pasted this code from the Sun Java Tutorial

http://java.sun.com/docs/books/tutorial/2d/basic2d/examples/ImageLabel.java

package sim;

/*
 * Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
are met:
 *
 * -Redistribution of source code must retain the above copyright
notice, this
 * list of conditions and the following disclaimer.
 *
 * -Redistribution in binary form must reproduce the above copyright
notice,
 * this list of conditions and the following disclaimer in the
documentation
 * and/or other materials provided with the distribution.
 *
 * Neither the name of Sun Microsystems, Inc. or the names of
contributors may
 * be used to endorse or promote products derived from this software
without
 * specific prior written permission.
 *
 * This software is provided "AS IS," without a warranty of any kind.
ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES,
INCLUDING
 * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
PURPOSE
 * OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MIDROSYSTEMS, INC.
("SUN")
 * AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY
LICENSEE
 * AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR
ITS
 * DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR
ANY LOST
 * REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL,
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 * INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF
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 */

import java.io.*;
import java.awt.*;
import java.awt.font.*;
import java.awt.geom.*;
import java.awt.image.*;
import javax.swing.*;
import javax.imageio.*;

public class ImageLabel extends Component {

    /**
     *
     */

    public static void main(String args[]) {

        JFrame frame = new JFrame("Image Label");
        BufferedImage img = null;
        try {
            String imageFileName = "painting.gif";
            img = ImageIO.read(new File(imageFileName));
        } catch (IOException e) {
        }
        frame.add("Center", new ImageLabel(img, "Java 2D Graphics!"));
        frame.pack(); // This is line 63 where the stack trace starts
        frame.setVisible(true);
    }

    BufferedImage img;
    String text;
    Font font;

    public ImageLabel(BufferedImage img, String text) {
        this.img = img;
        this.text = text;
        font = new Font("Serif", Font.PLAIN, 36);
    }

    /* We want to size the component around the text. */
    public Dimension getPreferredSize() {
        FontMetrics metrics = img.getGraphics().getFontMetrics(font);
        int width = metrics.stringWidth(text)*2;
        int height = metrics.getHeight()*2;
        return new Dimension(width, height);
    }

    public void paint(Graphics g) {

        /* Draw the image stretched to exactly cover the size of the
         * drawing area.
         */
        Dimension size = getSize();
        g.drawImage(img,
                    0, 0, size.width, size.height,
                    0, 0, img.getWidth(null), img.getHeight(null),
                    null);

        /* Fill a rounded rectangle centered in the drawing area.
         * Calculate the size of the rectangle from the size of the
text
         */
        g.setFont(font);
        FontRenderContext frc =
((Graphics2D)g).getFontRenderContext();
        Rectangle2D bounds = font.getStringBounds(text, frc);

        int wText = (int)bounds.getWidth();
        int hText = (int)bounds.getHeight();

        int rX = (size.width-wText)/2;
        int rY = (size.height-hText)/2;
        g.setColor(Color.yellow);
        g.fillRoundRect(rX, rY, wText, hText, hText/2, hText/2);

        /* Draw text positioned in the rectangle.
         * Since the rectangle is sized based on the bounds of
         * the String we can position it using those bounds.
         */
        int xText = rX-(int)bounds.getX();
        int yText = rY-(int)bounds.getY();
        g.setColor(Color.black);
        g.setFont(font);
        g.drawString(text, xText, yText);
    }
}

When I run it under Java 6 (jdk1.6.0) I get the following run-time
errors

Exception in thread "main" java.lang.NullPointerException
    at sim.ImageLabel.getPreferredSize(ImageLabel.java:79)
    at java.awt.BorderLayout.preferredLayoutSize(BorderLayout.java:702)
    at java.awt.Container.preferredSize(Container.java:1576)
    at java.awt.Container.getPreferredSize(Container.java:1561)
    at javax.swing.JComponent.getPreferredSize(JComponent.java:1609)
    at javax.swing.JRootPane
$RootLayout.preferredLayoutSize(JRootPane.java:898)
    at java.awt.Container.preferredSize(Container.java:1576)
    at java.awt.Container.getPreferredSize(Container.java:1561)
    at javax.swing.JComponent.getPreferredSize(JComponent.java:1609)
    at java.awt.BorderLayout.preferredLayoutSize(BorderLayout.java:702)
    at java.awt.Container.preferredSize(Container.java:1576)
    at java.awt.Container.getPreferredSize(Container.java:1561)
    at java.awt.Window.pack(Window.java:663)
    at sim.ImageLabel.main(ImageLabel.java:63)

I have no idea what could be causing this error so I'm hoping someone
can help me.
At first I *thought* the try..catch may be producing it, so I took
a .JPG image and put it in what I thought to be the correct place
(both at the root of the project and in the source directory) but to
no avail.

Thanks

J