UX: lotus state power CLI should fail if called with a not-miner

cli/state.go

@@ -281,17 +281,26 @@ var StatePowerCmd = &cli.Command{
 
 		ctx := ReqContext(cctx)
 
+		ts, err := LoadTipSet(ctx, cctx, api)
+		if err != nil {
+			return err
+		}
+
 		var maddr address.Address
 		if cctx.Args().Present() {
 			maddr, err = address.NewFromString(cctx.Args().First())
 			if err != nil {
 				return err
 			}
-		}
 
-		ts, err := LoadTipSet(ctx, cctx, api)
-		if err != nil {
-			return err
+			ma, err := api.StateGetActor(ctx, maddr, ts.Key())
+			if err != nil {
+				return err
+			}
+
+			if !builtin.IsStorageMinerActor(ma.Code) {
+				return xerrors.New("provided address does not correspond to a miner actor")
+			}
 		}
 
 		power, err := api.StateMinerPower(ctx, maddr, ts.Key())