Login Plugin throws NPE

Under certain conditions the LoginPlugin throws a NPE. The language drop down choice is setting a null value which is used to determine the locale for the session.

20.04.2011 14:13:56 ERROR [org.apache.wicket.RequestCycle.logRuntimeException():1529] Method onFormSubmitted of interface org.apache.wicket.markup.html.form.IFormSubmitListener targeted at component [MarkupContainer [Component id = signInForm]] threw an exception
org.apache.wicket.WicketRuntimeException: Method onFormSubmitted of interface org.apache.wicket.markup.html.form.IFormSubmitListener targeted at component [MarkupContainer [Component id = signInForm]] threw an exception
at org.apache.wicket.RequestListenerInterface.invoke(RequestListenerInterface.java:193)
at org.apache.wicket.request.target.component.listener.ListenerInterfaceRequestTarget.processEvents(ListenerInterfaceRequestTarget.java:73)
at org.apache.wicket.request.AbstractRequestCycleProcessor.processEvents(AbstractRequestCycleProcessor.java:92)
at org.hippoecm.frontend.PluginRequestCycleProcessor.processEvents(PluginRequestCycleProcessor.java:95)
at org.apache.wicket.RequestCycle.processEventsAndRespond(RequestCycle.java:1250)
at org.apache.wicket.RequestCycle.step(RequestCycle.java:1329)
at org.apache.wicket.RequestCycle.steps(RequestCycle.java:1436)
at org.apache.wicket.RequestCycle.request(RequestCycle.java:545)
at org.apache.wicket.protocol.http.WicketFilter.doGet(WicketFilter.java:486)
at org.apache.wicket.protocol.http.WicketFilter.doFilter(WicketFilter.java:319)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.hippoecm.frontend.ResourceRewriteFilter.doFilter(ResourceRewriteFilter.java:129)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.hippoecm.frontend.plugins.login.ConcurrentLoginFilter.doFilter(ConcurrentLoginFilter.java:54)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:857)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:396)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.GeneratedMethodAccessor345.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.apache.wicket.RequestListenerInterface.invoke(RequestListenerInterface.java:182)
... 29 more
Caused by: java.lang.NullPointerException
at java.util.Locale.toLowerCase(Unknown Source)
at java.util.Locale.convertOldISOCodes(Unknown Source)
at java.util.Locale.<init>(Unknown Source)
at java.util.Locale.<init>(Unknown Source)
at org.hippoecm.frontend.plugins.login.RememberMeLoginPlugin$SignInForm.onSubmit(RememberMeLoginPlugin.java:193)
at org.apache.wicket.markup.html.form.Form.delegateSubmit(Form.java:1572)
at org.apache.wicket.markup.html.form.Form.process(Form.java:960)
at org.apache.wicket.markup.html.form.Form.onFormSubmitted(Form.java:921)
... 33 more