chore: use String constructor instead of .toString for type conversion

Author: harryby1149

lib/layer.js

@@ -139,7 +139,7 @@ module.exports = class Layer {
     }
 
     for (const [key, value] of Object.entries(replace)) {
-      replace[key] = value.toString();
+      replace[key] = String(value);
     }
 
     replaced = toPath(replace);