FreeMarker template error

The following has evaluated to null or missing:
==> isPCSys  [in template "WEB-INF/common.ftl" at line 2701, column 14]

Tip: If the failing expression is known to be legally null/missing, either specify a default value with 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 parenthessis: (myOptionVar.foo)!myDefault, (myOptionVar.foo)??

The failing instruction (FTL stack trace):
----------
==> #if isPCSys && pcSysCountdown != "" &...  [in template "WEB-INF/common.ftl" in macro "goToUnionHomePage" at line 2701, column 9]
    @c.goToUnionHomePage  [in template "WEB-INF/common.ftl" in macro "jquery" at line 31, column 9]
    @c.jquery  [in template "template/error/runerror.html" at line 6, column 17]
----------

Java stack trace (for programmers):
----------
freemarker.core.InvalidReferenceException: [... Exception message was already printed; see it above ...]
	at freemarker.core.InvalidReferenceException.getInstance(InvalidReferenceException.java:98)
	at freemarker.core.UnexpectedTypeException.newDesciptionBuilder(UnexpectedTypeException.java:41)
	at freemarker.core.UnexpectedTypeException.<init>(UnexpectedTypeException.java:24)
	at freemarker.core.NonBooleanException.<init>(NonBooleanException.java:81)
	at freemarker.core.Expression.modelToBoolean(Expression.java:153)
	at freemarker.core.Expression.evalToBoolean(Expression.java:144)
	at freemarker.core.AndExpression.evalToBoolean(AndExpression.java:68)
	at freemarker.core.AndExpression.evalToBoolean(AndExpression.java:68)
	at freemarker.core.ConditionalBlock.accept(ConditionalBlock.java:84)
	at freemarker.core.Environment.visit(Environment.java:265)
	at freemarker.core.Macro$Context.runMacro(Macro.java:209)
	at freemarker.core.Environment.visit(Environment.java:694)
	at freemarker.core.UnifiedCall.accept(UnifiedCall.java:116)
	at freemarker.core.Environment.visit(Environment.java:265)
	at freemarker.core.MixedContent.accept(MixedContent.java:93)
	at freemarker.core.Environment.visit(Environment.java:265)
	at freemarker.core.Macro$Context.runMacro(Macro.java:209)
	at freemarker.core.Environment.visit(Environment.java:694)
	at freemarker.core.UnifiedCall.accept(UnifiedCall.java:116)
	at freemarker.core.Environment.visit(Environment.java:265)
	at freemarker.core.MixedContent.accept(MixedContent.java:93)
	at freemarker.core.Environment.visit(Environment.java:265)
	at freemarker.core.Environment.process(Environment.java:243)
	at freemarker.template.Template.process(Template.java:277)
	at freemarker.ext.servlet.FreemarkerServlet.process(FreemarkerServlet.java:452)
	at freemarker.ext.servlet.FreemarkerServlet.doGet(FreemarkerServlet.java:391)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:718)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:831)
	at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:1694)
	at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:1635)
	at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:113)
	at com.ibm.ws.webcontainer.filter.WebAppFilterChain._doFilter(WebAppFilterChain.java:80)
	at com.ibm.ws.webcontainer.filter.WebAppFilterManager.doFilter(WebAppFilterManager.java:908)
	at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:965)
	at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:508)
	at com.ibm.ws.webcontainer.servlet.ServletWrapperImpl.handleRequest(ServletWrapperImpl.java:181)
	at com.ibm.ws.webcontainer.webapp.WebAppRequestDispatcher.forward(WebAppRequestDispatcher.java:374)
	at com.topsoft.interceptor.LoginServlet.doGet(LoginServlet.java:144)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:718)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:831)
	at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:1694)
	at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:1635)
	at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:149)
	at com.topsoft.interceptor.IflytekFilter.doFilter(IflytekFilter.java:59)
	at com.ibm.ws.webcontainer.filter.FilterInstanceWrapper.doFilter(FilterInstanceWrapper.java:190)
	at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:125)
	at com.topsoft.interceptor.HttpHostFilter.doFilter(HttpHostFilter.java:44)
	at com.ibm.ws.webcontainer.filter.FilterInstanceWrapper.doFilter(FilterInstanceWrapper.java:190)
	at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:125)
	at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
	at com.ibm.ws.webcontainer.filter.FilterInstanceWrapper.doFilter(FilterInstanceWrapper.java:190)
	at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:125)
	at com.topsoft.interceptor.XssFilter.doFilter(XssFilter.java:23)
	at com.ibm.ws.webcontainer.filter.FilterInstanceWrapper.doFilter(FilterInstanceWrapper.java:190)
	at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:125)
	at com.ibm.ws.webcontainer.filter.WebAppFilterChain._doFilter(WebAppFilterChain.java:80)
	at com.ibm.ws.webcontainer.filter.WebAppFilterManager.doFilter(WebAppFilterManager.java:908)
	at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:965)
	at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:508)
	at com.ibm.ws.webcontainer.servlet.ServletWrapperImpl.handleRequest(ServletWrapperImpl.java:181)
	at com.ibm.ws.webcontainer.servlet.CacheServletWrapper.handleRequest(CacheServletWrapper.java:91)
	at com.ibm.ws.webcontainer.WebContainer.handleRequest(WebContainer.java:878)
	at com.ibm.ws.webcontainer.WSWebContainer.handleRequest(WSWebContainer.java:1592)
	at com.ibm.ws.webcontainer.channel.WCChannelLink.ready(WCChannelLink.java:191)
	at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleDiscrimination(HttpInboundLink.java:454)
	at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleNewRequest(HttpInboundLink.java:516)
	at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.processRequest(HttpInboundLink.java:307)
	at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.ready(HttpInboundLink.java:278)
	at com.ibm.ws.tcp.channel.impl.NewConnectionInitialReadCallback.sendToDiscriminators(NewConnectionInitialReadCallback.java:214)
	at com.ibm.ws.tcp.channel.impl.NewConnectionInitialReadCallback.complete(NewConnectionInitialReadCallback.java:113)
	at com.ibm.ws.tcp.channel.impl.AioReadCompletionListener.futureCompleted(AioReadCompletionListener.java:175)
	at com.ibm.io.async.AbstractAsyncFuture.invokeCallback(AbstractAsyncFuture.java:217)
	at com.ibm.io.async.AsyncChannelFuture$1.run(AsyncChannelFuture.java:205)
	at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:1662)

Error 500: javax.servlet.ServletException: Error executing FreeMarker template