Phaser 3. Importing phaser/src/core/Game produce error during runtime

[Chen Ling Xue]

The phaser game not starting error on 

import Game1 from "phaser/src/core/Game";
import { Game } from "phaser";
console.log(Game1, Game);
const app = new Game1(gameSettings);

But when I tried to check the output of the console, it gives the same instance

but when I tried to make use the one from the phaser js directly, no error found
 

import { Game } from "phaser";
const app = new Game(gameSettings);

Thanks in advance for answers which part I do wrong.