刚学习小游戏开发，参考模板小游戏，做一个简单的页面，放置一个背景图，模拟器上面可以呈现：

但上传体验版，就显示不了，黑屏：

请教问题出在哪里。

以下完整代码：

const WINDOW_INFO = wx.getWindowInfo();
const IMAGE_SRC="./images/index_bg.jpg";
const BACKGROUND_WIDTH = 1312;
const BACKGROUND_HEIGHT = 736; 
/**
 * 游戏主函数
 */
export default class Main { 
    constructor() {
        this.init();
    }
    
    /**
     * 初始化
     */
    init(){
         //创建画布
         this.canvas = wx.createCanvas();
         //获取canvas的2D绘图上下文，画笔 
         
         this.canvas.width = WINDOW_INFO.screenWidth;
         this.canvas.height = WINDOW_INFO.screenHeight;
         this.context  = this.canvas.getContext("2d");
         //设置背景图片
         this.image = wx.createImage();
         this.image.src= IMAGE_SRC;
         this.imageLoaded = false;
         this.image.onload=()=>{
              this.imageLoaded = true;
         };
         //将图片绘制到画布上， 并且渲染至屏幕
         requestAnimationFrame(this.render.bind(this));
         
    }


    /**
     * 绘制
     */
    render(){
          const timeId= setInterval(() => {
                   if(this.imageLoaded){
                        console.log('图片加载成功了');
                        clearInterval(timeId);
                        this.context.drawImage(
                            this.image,
                            0,
                            0,
                            BACKGROUND_WIDTH,
                            BACKGROUND_HEIGHT,
                            0,
                            0,
                            this.canvas.width,
                            this.canvas.height                  
                        ); 
                  }else{
                      console.log('图片加载中');
                  }
           }, 100);
    }
}