avoid file not exist error

go/topology/topology.go

@@ -53,9 +53,10 @@ func (t *Topology) loadConfiguration(configurationFile string) error {
 	b, e := ioutil.ReadFile(configurationFile)
 	if e == nil {
 		t.configuration, e = NewConfiguration(b)
-	}
 		return e
 	}
+	return nil
+}
 
 func (t *Topology) Lookup(vid storage.VolumeId) []*DataNode {
 	for _, vl := range t.replicaType2VolumeLayout {