fix: dont output if no secrets

cli/app/secret.go

@@ -249,7 +249,12 @@ var appSecretLsCommand = &cli.Command{
 			table.Append(tableRow)
 		}
 
-		table.Render()
+		if table.NumLines() > 0 {
+			table.Render()
+		} else {
+			logrus.Warnf("no secrets stored for %s", app.Name)
+		}
+
 		return nil
 	},
 	BashComplete: autocomplete.AppNameComplete,