Update lib/logger.js

Co-authored-by: Marco Ippolito <marcoippolito54@gmail.com>

Author: mertcanaltin

lib/logger.js

@@ -166,7 +166,7 @@ class JSONConsumer extends LogConsumer {
 
     // Add consumer fields
     const consumerFields = this.#fields;
-    for (const key in consumerFields) {
+    for (const key of ObjectKeys(consumerFields)) {
       const value = consumerFields[key];
       json += ',"' + key + '":';
       json += typeof value === 'string' ?