test: fix assertion message in test_async.c

PR-URL: nodejs#49146
Reviewed-By: Moshe Atlow <moshe@atlow.co.il>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

test/node-api/test_async/test_async.c

@@ -65,7 +65,7 @@ static napi_value Test(napi_env env, napi_callback_info info) {
   void* data;
   NODE_API_CALL(env,
     napi_get_cb_info(env, info, &argc, argv, &_this, &data));
-  NODE_API_ASSERT(env, argc >= 3, "Not enough arguments, expected 2.");
+  NODE_API_ASSERT(env, argc >= 3, "Not enough arguments, expected 3.");
 
   napi_valuetype t;
   NODE_API_CALL(env, napi_typeof(env, argv[0], &t));