correctly handle error callback (fix #614)
correctly handle error callback (fix #614)

wesley1001/commafeed,Hubcapp/commafeed,Hubcapp/commafeed,wesley1001/commafeed,Hubcapp/commafeed,RavenB/commafeed,ebraminio/commafeed,Athou/commafeed,ebraminio/commafeed,RavenB/commafeed,ahmadassaf/CommaFeed-RSS-Reader,Athou/commafeed,ebraminio/commafeed,ebraminio/commafeed,zhangzuoqiang/commafeed,RavenB/commafeed,syshk/commafeed,zhangzuoqiang/commafeed,syshk/commafeed,wesley1001/commafeed,ahmadassaf/CommaFeed-RSS-Reader,zhangzuoqiang/commafeed,RavenB/commafeed,Hubcapp/commafeed,ahmadassaf/CommaFeed-RSS-Reader,syshk/commafeed,Athou/commafeed,zhangzuoqiang/commafeed,wesley1001/commafeed,Athou/commafeed,syshk/commafeed,ahmadassaf/CommaFeed-RSS-Reader