The constructor of SunGraphics2D doesn't check if passed font is null
and calls checkFontInfo where the font is being accessed, which
could lead to NPE.

Here is a test case to reproduce the problem:
import java.awt.*;

public class Test extends Frame {
    public Test() {
        pack();
        setFont(null);
        Component c = new Component() {};
        c.setFont(null);
        add(c);
        Image im = c.createImage(10, 10);
        Graphics g = im.getGraphics();
    }
    public static void main(String argv[]) {
        new Test();
    }
}

The exception being thrown (on merlin beta_refresh b68):
Exception in thread "main" java.lang.NullPointerException
        at sun.java2d.SunGraphics2D.checkFontInfo(SunGraphics2D.java:578)
        at sun.java2d.SunGraphics2D.<init>(SunGraphics2D.java:229)
        at sun.awt.image.OffScreenImage.createGraphics(OffScreenImage.java:81)
        at sun.awt.image.OffScreenImage.initBackground(OffScreenImage.java:102)
        at sun.awt.image.OffScreenImage.<init>(OffScreenImage.java:70)
        at sun.awt.image.AcceleratedOffScreenImage.<init>(AcceleratedOffScreenImage.java:68)
        at sun.awt.motif.X11OffScreenImage.<init>(X11OffScreenImage.java:50)
        at sun.awt.motif.X11OffScreenImage.<init>(X11OffScreenImage.java:44)
        at sun.awt.motif.MComponentPeer.createImage(MComponentPeer.java:390)
        at java.awt.Component.createImage(Component.java:2573)
        at java.awt.Component.createImage(Component.java:2570)
        at Test.<init>(Test.java:10)
        at Test.main(Test.java:14)

dmitri.trembovetski@eng 2001-06-19