Display error when doing a search on back

java.lang.NullPointerException at org.apache.cocoon.xml.XMLUtils.data(XMLUtils.java:324) at org.apache.cocoon.xml.XMLUtils.createElement(XMLUtils.java:481) at org.ametys.web.frontoffice.AbstractSearchGenerator.saxPageHit(AbstractSearchGenerator.java:392) at org.ametys.web.frontoffice.SearchGenerator.saxHits(SearchGenerator.java:206) at org.ametys.web.frontoffice.AbstractSearchGenerator.search(AbstractSearchGenerator.java:228) at org.ametys.web.frontoffice.SearchGenerator.search(SearchGenerator.java:138) at org.ametys.web.frontoffice.AbstractSearchGenerator.generate(AbstractSearchGenerator.java:184) at org.apache.cocoon.components.pipeline.AbstractProcessingPipeline.processXMLPipeline(AbstractProcessingPipeline.java:579) at org.apache.cocoon.components.pipeline.impl.AbstractCachingProcessingPipeline.processXMLPipeline(AbstractCachingProcessingPipeline.java:280) at org.apache.cocoon.components.pipeline.AbstractProcessingPipeline.process(AbstractProcessingPipeline.java:780) at org.apache.cocoon.components.source.impl.SitemapSource.toSAX(SitemapSource.java:414) at org.apache.cocoon.components.source.SourceUtil.toSAX(SourceUtil.java:101) at org.apache.cocoon.components.source.SourceUtil.toSAX(SourceUtil.java:181) at org.apache.cocoon.components.source.SourceUtil.toSAX(SourceUtil.java:140) at org.ametys.web.repository.PageGenerator._saxZoneItems(PageGenerator.java:327) at org.ametys.web.repository.PageGenerator._saxZone(PageGenerator.java:219) at org.ametys.web.repository.PageGenerator.generate(PageGenerator.java:159) at org.apache.cocoon.components.pipeline.AbstractProcessingPipeline.processXMLPipeline(AbstractProcessingPipeline.java:579) at org.apache.cocoon.components.pipeline.impl.AbstractCachingProcessingPipeline.processXMLPipeline(AbstractCachingProcessingPipeline.java:280) at org.apache.cocoon.components.pipeline.AbstractProcessingPipeline.process(AbstractProcessingPipeline.java:780) at org.apache.cocoon.components.source.impl.SitemapSource.toSAX(SitemapSource.java:414) at org.apache.cocoon.components.source.SourceUtil.toSAX(SourceUtil.java:101) at org.apache.cocoon.components.source.SourceUtil.parse(SourceUtil.java:321) at org.apache.cocoon.sitemap.ContentAggregator.generate(ContentAggregator.java:125) at org.apache.cocoon.components.pipeline.AbstractProcessingPipeline.processXMLPipeline(AbstractProcessingPipeline.java:579) at org.apache.cocoon.components.pipeline.impl.AbstractCachingProcessingPipeline.processXMLPipeline(AbstractCachingProcessingPipeline.java:280) at org.apache.cocoon.components.pipeline.AbstractProcessingPipeline.process(AbstractProcessingPipeline.java:481) at org.apache.cocoon.components.treeprocessor.sitemap.SerializeNode.invoke(SerializeNode.java:144) at org.apache.cocoon.components.treeprocessor.AbstractParentProcessingNode.invokeNodes(AbstractParentProcessingNode.java:47) at org.apache.cocoon.components.treeprocessor.sitemap.MatchNode.invoke(MatchNode.java:108) at org.apache.cocoon.components.treeprocessor.AbstractParentProcessingNode.invokeNodes(AbstractParentProcessingNode.java:69) at org.apache.cocoon.components.treeprocessor.sitemap.PipelineNode.invoke(PipelineNode.java:143) at org.apache.cocoon.components.treeprocessor.AbstractParentProcessingNode.invokeNodes(AbstractParentProcessingNode.java:69) at org.apache.cocoon.components.treeprocessor.sitemap.PipelinesNode.invoke(PipelinesNode.java:93) at org.apache.cocoon.components.treeprocessor.ConcreteTreeProcessor.process(ConcreteTreeProcessor.java:235) at org.apache.cocoon.components.treeprocessor.ConcreteTreeProcessor.process(ConcreteTreeProcessor.java:177) at org.apache.cocoon.components.treeprocessor.TreeProcessor.process(TreeProcessor.java:254) at org.apache.cocoon.components.treeprocessor.sitemap.MountNode.invoke(MountNode.java:118) at org.apache.cocoon.components.treeprocessor.AbstractParentProcessingNode.invokeNodes(AbstractParentProcessingNode.java:47) at org.apache.cocoon.components.treeprocessor.sitemap.MatchNode.invoke(MatchNode.java:108) at org.apache.cocoon.components.treeprocessor.AbstractParentProcessingNode.invokeNodes(AbstractParentProcessingNode.java:69) at org.apache.cocoon.components.treeprocessor.sitemap.PipelineNode.invoke(PipelineNode.java:143) at org.apache.cocoon.components.treeprocessor.AbstractParentProcessingNode.invokeNodes(AbstractParentProcessingNode.java:69) at org.apache.cocoon.components.treeprocessor.sitemap.PipelinesNode.invoke(PipelinesNode.java:93) at org.apache.cocoon.components.treeprocessor.ConcreteTreeProcessor.process(ConcreteTreeProcessor.java:235) at org.apache.cocoon.components.treeprocessor.ConcreteTreeProcessor.process(ConcreteTreeProcessor.java:177) at org.apache.cocoon.components.treeprocessor.TreeProcessor.process(TreeProcessor.java:254) at org.apache.cocoon.Cocoon.process(Cocoon.java:699) at org.apache.cocoon.servlet.CocoonServlet.service(CocoonServlet.java:1159) at org.ametys.runtime.servlet.RuntimeServlet._doService(RuntimeServlet.java:134) at org.ametys.runtime.servlet.RuntimeServlet.service(RuntimeServlet.java:91) at javax.servlet.http.HttpServlet.service(HttpServlet.java:820) at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511) at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:390) at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216) at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182) at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765) at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418) at org.mortbay.jetty.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:230) at org.mortbay.jetty.handler.HandlerCollection.handle(HandlerCollection.java:114) at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152) at org.mortbay.jetty.Server.handle(Server.java:326) at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:536) at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:930) at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:747) at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:218) at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:405) at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:409) at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:582)