Konqueror 4.8.4 can't create ZK sessions because the version extraction from the HTTP "user-agent" header fails.

partial HTTP header:
user-agent: Mozilla/5.0 (X11; Linux x86_64) KHTML/4.8.4 (like Gecko) Konqueror/4.8

causes:
SEVERE: Servlet.service() for servlet [zkLoader] in context with path [/demo] threw exception
java.lang.NullPointerException
at org.zkoss.web.servlet.Servlets.getVersion(Servlets.java:460)
at org.zkoss.web.servlet.Servlets.getVersion(Servlets.java:457)
at org.zkoss.web.servlet.Servlets.browserInfo(Servlets.java:419)
at org.zkoss.web.servlet.Servlets.browserInfo(Servlets.java:363)
at org.zkoss.web.servlet.Servlets.getBrowser(Servlets.java:325)
at org.zkoss.zk.ui.http.ExecutionImpl.<init>(ExecutionImpl.java:102)
at org.zkoss.zk.ui.http.TemporaryExecution.<init>(TemporaryExecution.java:41)
at org.zkoss.zk.ui.http.WebManager.newDesktop(WebManager.java:475)
at org.zkoss.zk.ui.http.WebManager.getDesktop(WebManager.java:461)
at org.zkoss.zk.ui.http.DHtmlLayoutServlet.process(DHtmlLayoutServlet.java:186)
at org.zkoss.zk.ui.http.DHtmlLayoutServlet.doGet(DHtmlLayoutServlet.java:135)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:225)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:581)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1001)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:579)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
at java.lang.Thread.run(Thread.java:679)