Fix NumberFormatException in messages.jsp type checking

[Copilot]

NumberFormatException: For input string: "class" thrown when entering citations. The EL expression ${errors.class.simpleName} fails in Tomcat 9+ because when errors is a List, the EL resolver interprets .class as a list index access and tries to parse "class" as an integer.

Changes

• Replace EL-based type checking with scriptlet instanceof String check in messages.jsp
• Same fix applied for both errors and messages variables

Before

<c:when test="${errors.class.simpleName eq 'String'}">

After

<% Object errorsObj = request.getAttribute("errors");
   if (errorsObj == null) errorsObj = session.getAttribute("errors");
   boolean errorsIsString = errorsObj instanceof String;
   request.setAttribute("errorsIsString", errorsIsString);
%>
<c:when test="${errorsIsString}">

Original prompt

I try to enter a citation and:

Yikes!
java.lang.NumberFormatException: For input string: "class"
at java.base/java.lang.NumberFormatException.forInputString(NumberFormatException.java:67)
at java.base/java.lang.Integer.parseInt(Integer.java:668)
at java.base/java.lang.Integer.parseInt(Integer.java:786)
at javax.el.ListELResolver.coerce(ListELResolver.java:144)
at javax.el.ListELResolver.getValue(ListELResolver.java:64)
at org.apache.jasper.el.JasperELResolver.getValue(JasperELResolver.java:123)
at org.apache.el.parser.AstValue.getValue(AstValue.java:160)
at org.apache.el.parser.AstEqual.getValue(AstEqual.java:33)
at org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:149)
at org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate(PageContextImpl.java:655)
at org.apache.jsp.decorators.defaultTemplate_jsp._jspx_meth_c_005fwhen_005f0(defaultTemplate_jsp.java:1227)
at org.apache.jsp.decorators.defaultTemplate_jsp._jspx_meth_c_005fchoose_005f0(defaultTemplate_jsp.java:1198)
at org.apache.jsp.decorators.defaultTemplate_jsp._jspx_meth_c_005fif_005f1(defaultTemplate_jsp.java:1165)
at org.apache.jsp.decorators.defaultTemplate_jsp._jspService(defaultTemplate_jsp.java:439)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:62)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:623)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:438)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:349)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:300)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:623)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:197)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:142)
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:619)
at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:496)
at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:444)
at com.opensymphony.module.sitemesh.filter.PageFilter.writeDecorator(PageFilter.java:173)
at com.opensymphony.module.sitemesh.filter.PageFilter.applyDecorator(PageFilter.java:158)
at com.opensymphony.module.sitemesh.filter.PageFilter.doFilter(PageFilter.java:62)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:166)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:142)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:352)
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:117)
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:83)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:361)
at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:164)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:361)
at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:126)
at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:120)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:361)
at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:131)
at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:85)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:361)
at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:100)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:361)
at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:63)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:361)
at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:227)
at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:221)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:361)
at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:107)
at org.springframework.security.web.authen...

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