DefineObjectsTag throws NPE when included in ErrorPageXXX.jsp

If <hst:defineObjects/> tag is included in non-hst-request processing, then it throws NPE like the following:

Aug 14, 2013 12:00:00 AM org.apache.catalina.core.ApplicationDispatcher invoke
SEVERE: Servlet.service() for servlet jsp threw exception
java.lang.NullPointerException
at org.hippoecm.hst.tag.DefineObjectsTag.doStartTag(DefineObjectsTag.java:70)
at org.apache.jsp.WEB_002dINF.jsp.errorpages.ErrorPage404_jsp._jspService(ErrorPage404_jsp.java:80)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:388)
...

It would be better to avoid NPE even in that kind of condition.