FreeMarker template error (HTML_DEBUG mode; use RETHROW in production!)

The following has evaluated to null or missing:
==> ccat  [in template "WEB-INF/views/front/list_news.htm" at line 1, column 85]

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Tip: If the failing expression is known to legally refer to something that's sometimes null or missing, either specify a default value like myOptionalVar!myDefault, or use <#if myOptionalVar??>when-present<#else>when-missing</#if>. (These only cover the last step of the expression; to cover the whole expression, use parenthesis: (myOptionalVar.foo)!myDefault, (myOptionalVar.foo)??
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FTL stack trace ("~" means nesting-related):
	- Failed at: #assign fcat = ccat  [in template "WEB-INF/views/front/list_news.htm" at line 1, column 71]
	- Reached through: @Category dirname=Parameters.cat; ccat  [in template "WEB-INF/views/front/list_news.htm" at line 1, column 29]
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Java stack trace (for programmers):
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freemarker.core.InvalidReferenceException: [... Exception message was already printed; see it above ...]
	at freemarker.core.InvalidReferenceException.getInstance(InvalidReferenceException.java:134)
	at freemarker.core.Assignment.accept(Assignment.java:139)
	at freemarker.core.Environment.visit(Environment.java:383)
	at freemarker.core.Environment$NestedElementTemplateDirectiveBody.render(Environment.java:3274)
	at com.chujian.platform.web.tags.CategoryTag.execute(CategoryTag.java:85)
	at freemarker.core.Environment.visit(Environment.java:464)
	at freemarker.core.UnifiedCall.accept(UnifiedCall.java:102)
	at freemarker.core.Environment.visit(Environment.java:347)
	at freemarker.core.Environment.visit(Environment.java:353)
	at freemarker.core.Environment.visit(Environment.java:353)
	at freemarker.core.Environment.process(Environment.java:326)
	at freemarker.template.Template.process(Template.java:383)
	at org.apache.struts2.views.freemarker.FreemarkerResult.doExecute(FreemarkerResult.java:184)
	at org.apache.struts2.result.StrutsResultSupport.execute(StrutsResultSupport.java:206)
	at com.opensymphony.xwork2.DefaultActionInvocation.executeResult(DefaultActionInvocation.java:375)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:279)
	at org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:250)
	at com.google.inject.struts2.Struts2Factory$ProvidedInterceptor.intercept(Struts2Factory.java:237)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
	at com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:179)
	at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:99)
	at com.google.inject.struts2.Struts2Factory$ProvidedInterceptor.intercept(Struts2Factory.java:237)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
	at com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:263)
	at org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:49)
	at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:99)
	at com.google.inject.struts2.Struts2Factory$ProvidedInterceptor.intercept(Struts2Factory.java:237)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
	at com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.doIntercept(ConversionErrorInterceptor.java:142)
	at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:99)
	at com.google.inject.struts2.Struts2Factory$ProvidedInterceptor.intercept(Struts2Factory.java:237)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
	at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:140)
	at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:99)
	at com.google.inject.struts2.Struts2Factory$ProvidedInterceptor.intercept(Struts2Factory.java:237)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
	at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:140)
	at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:99)
	at com.google.inject.struts2.Struts2Factory$ProvidedInterceptor.intercept(Struts2Factory.java:237)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
	at com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:201)
	at com.google.inject.struts2.Struts2Factory$ProvidedInterceptor.intercept(Struts2Factory.java:237)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
	at org.apache.struts2.interceptor.MultiselectInterceptor.intercept(MultiselectInterceptor.java:67)
	at com.google.inject.struts2.Struts2Factory$ProvidedInterceptor.intercept(Struts2Factory.java:237)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
	at org.apache.struts2.interceptor.DateTextFieldInterceptor.intercept(DateTextFieldInterceptor.java:133)
	at com.google.inject.struts2.Struts2Factory$ProvidedInterceptor.intercept(Struts2Factory.java:237)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
	at org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:89)
	at com.google.inject.struts2.Struts2Factory$ProvidedInterceptor.intercept(Struts2Factory.java:237)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
	at org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:243)
	at com.google.inject.struts2.Struts2Factory$ProvidedInterceptor.intercept(Struts2Factory.java:237)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
	at com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:101)
	at com.google.inject.struts2.Struts2Factory$ProvidedInterceptor.intercept(Struts2Factory.java:237)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
	at com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:142)
	at com.google.inject.struts2.Struts2Factory$ProvidedInterceptor.intercept(Struts2Factory.java:237)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
	at com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:160)
	at com.google.inject.struts2.Struts2Factory$ProvidedInterceptor.intercept(Struts2Factory.java:237)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
	at com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:175)
	at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:99)
	at com.google.inject.struts2.Struts2Factory$ProvidedInterceptor.intercept(Struts2Factory.java:237)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
	at org.apache.struts2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:121)
	at com.google.inject.struts2.Struts2Factory$ProvidedInterceptor.intercept(Struts2Factory.java:237)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
	at org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:167)
	at com.google.inject.struts2.Struts2Factory$ProvidedInterceptor.intercept(Struts2Factory.java:237)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
	at com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:207)
	at com.google.inject.struts2.Struts2Factory$ProvidedInterceptor.intercept(Struts2Factory.java:237)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
	at com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:196)
	at com.google.inject.struts2.Struts2Factory$ProvidedInterceptor.intercept(Struts2Factory.java:237)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
	at org.apache.struts2.factory.StrutsActionProxy.execute(StrutsActionProxy.java:48)
	at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:574)
	at org.apache.struts2.dispatcher.ExecuteOperations.executeAction(ExecuteOperations.java:79)
	at org.apache.struts2.dispatcher.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:141)
	at com.google.inject.servlet.FilterChainInvocation.doFilter(FilterChainInvocation.java:82)
	at com.cj.sgiframe.struts.filters.CharacterEncodingFilter.doFilter(CharacterEncodingFilter.java:33)
	at com.google.inject.servlet.FilterChainInvocation.doFilter(FilterChainInvocation.java:82)
	at com.google.inject.servlet.ManagedFilterPipeline.dispatch(ManagedFilterPipeline.java:121)
	at com.google.inject.servlet.GuiceFilter.doFilter(GuiceFilter.java:133)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.apache.shiro.guice.web.SimpleFilterChain.doFilter(SimpleFilterChain.java:44)
	at com.chujian.platform.web.filters.ShiroFiter.doFilter(ShiroFiter.java:36)
	at org.apache.shiro.guice.web.SimpleFilterChain.doFilter(SimpleFilterChain.java:41)
	at org.apache.shiro.web.servlet.AdviceFilter.executeChain(AdviceFilter.java:108)
	at org.apache.shiro.web.servlet.AdviceFilter.doFilterInternal(AdviceFilter.java:137)
	at org.apache.shiro.web.servlet.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:125)
	at org.apache.shiro.guice.web.SimpleFilterChain.doFilter(SimpleFilterChain.java:41)
	at org.apache.shiro.web.servlet.AbstractShiroFilter.executeChain(AbstractShiroFilter.java:450)
	at org.apache.shiro.web.servlet.AbstractShiroFilter$1.call(AbstractShiroFilter.java:365)
	at org.apache.shiro.subject.support.SubjectCallable.doCall(SubjectCallable.java:90)
	at org.apache.shiro.subject.support.SubjectCallable.call(SubjectCallable.java:83)
	at org.apache.shiro.subject.support.DelegatingSubject.execute(DelegatingSubject.java:387)
	at org.apache.shiro.web.servlet.AbstractShiroFilter.doFilterInternal(AbstractShiroFilter.java:362)
	at org.apache.shiro.web.servlet.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:125)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at com.chujian.platform.web.filters.URLFilter.doFilter(URLFilter.java:53)
	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.ApplicationDispatcher.invoke(ApplicationDispatcher.java:646)
	at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:436)
	at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:374)
	at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:302)
	at com.chujian.platform.web.filters.URLFilter.doFilter(URLFilter.java:59)
	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.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:470)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
	at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:861)
	at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:606)
	at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
	at java.lang.Thread.run(Thread.java:748)