NullPointerException occurs if L&F is changed while Text is loading in SwingSet

In the SwingSet demo, click on ProgressBar, then click on Start
Loading Text.
Change the L&F to Rose while text is loading.

The following exception occurs:
java.lang.NullPointerException
at com.sun.java.swing.text.JPlainView.lineToRect(JPlainView.java:307)
at com.sun.java.swing.text.JPlainView.damageLineRange(JPlainView.java:299)
at com.sun.java.swing.text.JPlainView.updateDamage(JPlainView.java:238)
at com.sun.java.swing.text.JPlainView.insertUpdate(JPlainView.java:200)
at com.sun.java.swing.text.JTextUI$JViewFactory.insertUpdate(JTextUI.java:411)
at com.sun.java.swing.text.JTextUI$JTextView.insertUpdate(JTextUI.java:741)
at com.sun.java.swing.text.JDocument.externalNotifyInsert(JDocument.java:470)
at com.sun.java.swing.text.JDocument.insertString(JDocument.java:173)
at com.sun.java.swing.text.JDocument.insertString(JDocument.java:156)
at com.sun.java.swing.JTextArea.append(JTextArea.java:183)
at ProgressPanel$LoadThread.run(ProgressPanel.java:155)


JDK 1.1.4 and Swing 0.2 are being used.