cmd/loop: fix panic on zero index in instantout reservation selection

Author: Olexandr88

cmd/loop/instantout.go

@@ -137,7 +137,7 @@ func instantOut(ctx context.Context, cmd *cli.Command) error {
 			if err != nil {
 				return err
 			}
-			if idx < 0 {
+			if idx <= 0 {
 				return fmt.Errorf("invalid index %v", idx)
 			}