chore(standby_server): remove error return

because standby server should be started in best efforts.

etcd/etcd.go

@@ -231,9 +231,7 @@ func (e *Etcd) Run() {
 		ClientURL:  e.Config.Addr,
 		DataDir:    e.Config.DataDir,
 	}
-	if e.StandbyServer, err = server.NewStandbyServer(ssConfig, client); err != nil {
-		log.Fatal("error new standby server:", err)
-	}
+	e.StandbyServer = server.NewStandbyServer(ssConfig, client)
 
 	// Generating config could be slow.
 	// Put it here to make listen happen immediately after peer-server starting.

server/standby_server.go

@@ -50,16 +50,16 @@ type StandbyServer struct {
 	sync.Mutex
 }
 
-func NewStandbyServer(config StandbyServerConfig, client *Client) (*StandbyServer, error) {
+func NewStandbyServer(config StandbyServerConfig, client *Client) *StandbyServer {
 	s := &StandbyServer{
 		Config:      config,
 		client:      client,
 		standbyInfo: standbyInfo{SyncInterval: DefaultSyncInterval},
 	}
 	if err := s.loadInfo(); err != nil {
-		return nil, fmt.Errorf("error load standby info file: %v", err)
+		log.Warnf("error load standby info file: %v", err)
 	}
-	return s, nil
+	return s
 }
 
 func (s *StandbyServer) Start() {