fix bug

modules/storage/obs.go

@@ -60,7 +60,7 @@ func ObsHasObject(path string) (bool, error) {
 }
 
 func listAllParts(uuid, uploadID, key string) (output *obs.ListPartsOutput, err error) {
-	output = nil
+	output = &obs.ListPartsOutput{}
 	partNumberMarker := 0
 	for {
 		temp, err := ObsCli.ListParts(&obs.ListPartsInput{