avoid infinite loop

fix https://github.com/seaweedfs/seaweedfs/issues/4195#issuecomment-1426100904

weed/shell/command_volume_balance.go

@@ -330,7 +330,7 @@ func maybeMoveOneVolume(commandEnv *CommandEnv, volumeReplicas map[uint32][]*Vol
 	}
 
 	if candidateVolume.RemoteStorageName != "" {
-		return false, nil
+		return false, fmt.Errorf("does not move volume in remove storage")
 	}
 
 	if candidateVolume.ReplicaPlacement > 0 {