DefaultStrategy NPE when ListPrices null

12:47:14,645 ERROR DefaultExceptionMapper:114 - Unexpected error occurred
java.lang.NullPointerException
at org.yes.cart.shoppingcart.impl.DefaultAmountCalculationStrategy.calculateSubTotal(DefaultAmountCalculationStrategy.java:171)
at org.yes.cart.shoppingcart.impl.ShoppingCartImpl.getCartSubTotal(ShoppingCartImpl.java:243)
at ua.lana.web.page.lana1.component.cart.ShoppingCartView.<init>(ShoppingCartView.java:70)
at ua.lana.web.page.lana1.ShoppingCartPage.onBeforeRender(ShoppingCartPage.java:64)
at org.apache.wicket.Component.internalBeforeRender(Component.java:994)
at org.apache.wicket.Component.beforeRender(Component.java:1028)
at org.apache.wicket.Component.internalPrepareForRender(Component.java:2229)
at org.apache.wicket.Page.internalPrepareForRender(Page.java:279)
at org.apache.wicket.Component.render(Component.java:2313)
at org.apache.wicket.Page.renderPage(Page.java:1035)
at org.apache.wicket.request.handler.render.WebPageRenderer.renderPage(WebPageRenderer.java:115)
at org.apache.wicket.request.handler.render.WebPageRenderer.respond(WebPageRenderer.java:237)
at org.apache.wicket.request.handler.RenderPageRequestHandler.respond(RenderPageRequestHandler.java:167)
at org.apache.wicket.request.cycle.RequestCycle$HandlerExecutor.respond(RequestCycle.java:784)
at org.apache.wicket.request.RequestHandlerStack.execute(RequestHandlerStack.java:64)
at org.apache.wicket.request.cycle.RequestCycle.execute(RequestCycle.java:255)
at org.apache.wicket.request.cycle.RequestCycle.processRequest(RequestCycle.java:212)
at org.apache.wicket.request.cycle.RequestCycle.processRequestAndDetach(RequestCycle.java:283)
at org.apache.wicket.protocol.http.WicketFilter.processRequest(WicketFilter.java:188)
at org.apache.wicket.protocol.http.WicketFilter.doFilter(WicketFilter.java:244)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.yes.cart.web.filter.AbstractFilter.doFilter(AbstractFilter.java:62)
at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:346)
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:259)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.yes.cart.web.filter.AbstractFilter.doFilter(AbstractFilter.java:62)
at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:346)
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:259)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:936)
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:1004)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:1822)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662)