VOL-2170 add common method the output GRPC status error

Change-Id: Ibc48cb087cd73f981542bcb137bdb4f213fa7e8d
diff --git a/internal/pkg/commands/flows.go b/internal/pkg/commands/flows.go
index bfb82dc..b8c2eb6 100644
--- a/internal/pkg/commands/flows.go
+++ b/internal/pkg/commands/flows.go
@@ -117,7 +117,7 @@
 	case "device-flows":
 	case "logical-device-flows":
 	default:
-		panic(fmt.Errorf("Unknown method name: '%s'", options.Method))
+		Error.Fatalf("Unknown method name: '%s'", options.Method)
 	}
 
 	descriptor, method, err := GetMethod(options.Method)