Updates test case for new Error instance being returned.
Updates test case for new Error instance being returned.

hobbyquaker/homematic-xmlrpc,Growmies/node-xmlrpc,patricklodder/node-xmlrpc,AfterShip/node-xmlrpc,MiniGod/node-gbxremote,baalexander/node-xmlrpc,bolster/node-xmlrpc,xmlrpc-js/xmlrpc-marshalling