If this place is false, it will report an error, so you should delete the useless code. (#2458)

lib/core/dispatchRequest.js

@@ -37,7 +37,7 @@ module.exports = function dispatchRequest(config) {
   config.headers = utils.merge(
     config.headers.common || {},
     config.headers[config.method] || {},
-    config.headers || {}
+    config.headers
   );
 
   utils.forEach(