fix interconnect RPC error handling of graph
fix interconnect RPC error handling of graph

jubatus/jubatus,Asuka52/jubatus,gintenlabo/jubatus,gintenlabo/jubatus,kmaehashi/jubatus,kmaehashi/jubatus,rimms/jubatus,jubatus/jubatus,roselleebarle04/jubatus,roselleebarle04/jubatus,Asuka52/jubatus,mathn/jubatus,elkingtonmcb/jubatus,rimms/jubatus,mathn/jubatus,elkingtonmcb/jubatus,jubatus/jubatus