apply code change suggestion from @legendecas

Author: vmoroz

src/node_api.cc

@@ -625,13 +625,13 @@ static void napi_module_register_cb(v8::Local<v8::Object> exports,
                                     v8::Local<v8::Value> module,
                                     v8::Local<v8::Context> context,
                                     void* priv) {
+  const napi_module* napi_mod = static_cast<const napi_module*>(priv);
   napi_module_register_by_symbol(
       exports,
       module,
       context,
-      static_cast<const napi_module*>(priv)->nm_register_func,
-      static_cast<int32_t>(
-          static_cast<const napi_module*>(priv)->nm_api_version));
+      napi_mod->nm_register_func,
+      static_cast<int32_t>(napi_mod->nm_api_version));
 }
 
 void napi_module_register_by_symbol(v8::Local<v8::Object> exports,