Removed unnecessary return with typo

refs: https://github.com/TryGhost/Ghost/pull/12735

- this property doesn't exist - it should be this.resourcesConfig
- but we don't use the return value, so simply removed it

core/frontend/services/url/Resources.js

@@ -49,7 +49,7 @@ class Resources {
      */
     _initResourceConfig() {
         if (!_.isEmpty(this.resourcesConfig)) {
-            return this.resourceConfig;
+            return;
         }
 
         const bridge = require('../../../bridge');