Fix error while IQ error packet fails to be handled

When an IQ error is sent to Wildfire and the server is not able to handle it another IQ error will be attempted to be created to inform the sender that the IQ error failed to be delivered. This is creating the following exception:

2006.11.02 12:31:03 [org.jivesoftware.wildfire.IQRouter.handle(IQRouter.java:309)] Could not route packet
java.lang.IllegalArgumentException: IQ must be of type 'set' or 'get'. Original IQ: <iq type="error" id="0Ww13-17" from="workgroup.jivesoftware.com" to="matt@jivesoftware.com/spark"><workgroups xmlns="http://jabber.org/protocol/workgroup" jid="matt@jivesoftware.com/spark"/><error code="401" type="auth"><not-authorized xmlns="urn:ietf:params:xml:ns:xmpp-stanzas"/></error></iq>
at org.xmpp.packet.IQ.createResultIQ(IQ.java:322)
at org.jivesoftware.wildfire.IQRouter.sendErrorPacket(IQRouter.java:322)
at org.jivesoftware.wildfire.IQRouter.handle(IQRouter.java:304)
at org.jivesoftware.wildfire.IQRouter.route(IQRouter.java:96)
at org.jivesoftware.wildfire.spi.PacketRouterImpl.route(PacketRouterImpl.java:67)
at org.jivesoftware.wildfire.spi.PacketRouterImpl.route(PacketRouterImpl.java:59)
at org.jivesoftware.wildfire.component.InternalComponentManager.sendPacket(InternalComponentManager.java:160)
at com.jivesoftware.xmpp.workgroup.WorkgroupManager.send(WorkgroupManager.java:872)
at com.jivesoftware.xmpp.workgroup.WorkgroupManager.process(WorkgroupManager.java:774)
at com.jivesoftware.xmpp.workgroup.WorkgroupManager.processPacket(WorkgroupManager.java:655)
at org.jivesoftware.wildfire.component.InternalComponentManager$RoutableComponent.process(InternalComponentManager.java:435)