When you look the viewsource you can see the error.jsp is dumped at the end of the page
The error.jsp is not included in the list.jsp.
The buffer is cleared and the control is transferred to error.jsp.
The only thing
you should see is error.jsp
And one more thing, in your web.xml either use the error-code or exception-type but not both.
Also since the list.jsp defines the error page(not good programming, but OK for testing purpose), it is not required to be present in the web.xml.
Consider modifying your web.xml.
Hope this helps