fix localCache assertion

Author: tmacro

lib/Config.js

@@ -1841,7 +1841,7 @@ class Config extends EventEmitter {
         if (config.rateLimiting?.enabled) {
             // rate limiting uses the same localCache config defined for S3 to avoid
             // config duplication.
-            assert(config.localCache, 'missing required property of rateLimit ' +
+            assert(this.localCache, 'missing required property of rateLimit ' +
                 'configuration: localCache');
 
             this.rateLimiting.enabled = true;