org.apache.jasper.JasperException: An exception occurred processing [v4/common/Main.jsp] at line [49]

46:     //Get list of current adverts
47:     AdvertList advertList = screen.getAdvertList();                 //Adverts for normal listing
48:     AdvertList promotedAdvertList = screen.getPromotedAdvertList(); //Adverts to display in side-panels
49:     AdvertList popularAdvertList = screen.getPopularAdvertList();   //Adverts to display as popular
50:     AdvertList paidAdvertList = screen.getPaidAdvertList();   //Adverts to display as popular
51:     AdvertList kidsAdvertList = screen.getKidsAdvertList();         //Adverts to display as popular among kids
52:     Vector galleryList = screen.getGalleryImageList();


Stacktrace:
	at org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:610)
	at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:499)
	at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:379)
	at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:327)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:623)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:209)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:153)
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:178)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:153)
	at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:661)
	at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:425)
	at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:357)
	at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:294)
	at com.extras.v4.shared.control.Controller.processRequest(Unknown Source)
	at com.extras.v4.shared.control.Controller.doGet(Unknown Source)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:529)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:623)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:209)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:153)
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:178)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:153)
	at com.extras.v4.filters.BlockFilter.doFilter(Unknown Source)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:178)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:153)
	at load.ActionCounterFilter.doFilter(Unknown Source)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:178)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:153)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:167)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:90)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:481)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:130)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:93)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
	at org.apache.coyote.ajp.AjpProcessor.service(AjpProcessor.java:422)
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:63)
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:926)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1790)
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:52)
	at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191)
	at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.base/java.lang.Thread.run(Thread.java:840)
Caused by: java.lang.NullPointerException: Cannot invoke "com.extras.v4.shared.model.advert.AdvertList.size()" because "<local3>" is null
	at com.extras.v4.util.MainCache.getPopularAdvertListNotPaying(Unknown Source)
	at com.extras.v4.common.screens.MainScreen.getPopularAdvertList(Unknown Source)
	at org.apache.jsp.v4.common.Main_jsp._jspService(Main_jsp.java:217)
	at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:623)
	at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:466)
	... 43 more