问Phaser.JS中的物理错误

EN

var gameState = {};
var gx = 0;
function preload() {
    this.load.image('grass', 'grass.png');
    this.load.image('sky', 'sky.jpg');
    this.load.image('mario', 'mario.jpg');
}
function create() {
    var sky = this.add.image(window.innerWidth / 2, window.innerHeight / 2, 'sky');
     gameState.mario = this.physics.add.sprite(100,100, 'mario');
    sky.setScale(3.3);
    gameState.mario.setScale(.3);
    const platforms = this.physics.add.staticGroup();
    platforms.create(0,600, 'grass');
    gameState.mario.setCollideWorldBounds(true);
    this.physics.add.collider(gameState.mario, platforms);
}
function update() {
    
}
var config = {
    width: 400,
    height: 600,
    backgroundColor: 0x00FF00,
    scene: {
        preload, 
        create,
        update
    },
    physics: {
        default: 'arcade',
        arcade: {
            gravity: {y: 100},
            debug: false
        }
    }
};
var game = new Phaser.Game(config);