Update lib/logger.js

Co-authored-by: Chemi Atlow <[email protected]>

Author: mertcanaltin

lib/logger.js

@@ -293,7 +293,7 @@ class Logger {
       };
     } else if (typeof msgOrObj === 'string') {
       msg = msgOrObj;
-      logFields = fields || {};
+      logFields = fields || kEmptyObject;
       validateObject(logFields, 'fields');
     } else {
       validateObject(msgOrObj, 'obj');