another initializer crash

backtrace

C:\dev\ruby\sensible-cinema\bin>c:\dev\ruby\downloads\jruby\bin\jruby.exe -v crash7.rb
jruby 1.6.0.dev (ruby 1.8.7 patchlevel 249) (2010-11-18 2e438b1) (Java HotSpot(TM) Client VM 1.6.0_18) [Windows 7-x86-java]
Java.java:726:in `call': java.lang.NullPointerException
        from JavaMethod.java:630:in `call'
        from CachingCallSite.java:323:in `cacheAndCall'
        from CachingCallSite.java:161:in `callBlock'
        from CachingCallSite.java:166:in `call'
        from ConcreteJavaProxy.java:43:in `call'
        from SuperCallSite.java:336:in `cacheAndCall'
        from SuperCallSite.java:162:in `callBlock'
        from SuperCallSite.java:167:in `call'
        from crash7.rb:9:in `method__2$RUBY$initialize'
        from crash7Invokermethod__2$RUBY$initializeFixed0#initialize:65535:in `call'
        from CachingCallSite.java:303:in `cacheAndCall'
        from CachingCallSite.java:121:in `callBlock'
        from CachingCallSite.java:126:in `call'
        from RubyClass.java:810:in `call'
        from DynamicMethod.java:180:in `call'
        from ConcreteJavaProxy.java:132:in `call'
        from CachingCallSite.java:293:in `cacheAndCall'
        from CachingCallSite.java:112:in `call'
        from crash7.rb:12:in `module__0$RUBY$SensibleSwing'
        from crash7.rb:-1:in `module__0$RUBY$SensibleSwing'
        from crash7.rb:2:in `__file__'
        from crash7.rb:-1:in `load'
        from Ruby.java:688:in `runScript'
        from Ruby.java:571:in `runNormally'
        from Ruby.java:414:in `runFromMain'
        from Main.java:304:in `run'
        from Main.java:144:in `run'
        from Main.java:113:in `main'

reproduce.rb

require 'java'
module SensibleSwing
 include_package 'javax.swing'
 [JButton, JFrame, JLabel, JPanel, JOptionPane,
   JFileChooser, JComboBox, JDialog] # grab these constants (http://jira.codehaus.org/browse/JRUBY-5107)

class GetDisk < JDialog
   def initialize
     super "Pick your DVD drive"
    end
 end
GetDisk.new
end