小白一枚，按着教程尝试使用egret发布微信小游戏时碰到了如下报错，我也不知道是哪一段代码有问题因为这个'isCanvas'应该是egret里面所带的代码，麻烦各位大神帮忙看看，太谢谢啦！

gameThirdScriptError

Cannot set property 'isCanvas' of undefined

TypeError: Cannot set property 'isCanvas' of undefined

    at http://127.0.0.1:35203/game/egret.wxgame.js:6067:33

    at require (http://127.0.0.1:35203/game/__dev__/WAGame.js:2:94321)

    at http://127.0.0.1:35203/game/__dev__/WAGame.js:2:93931

    at http://127.0.0.1:35203/game/game.js:6:1

    at require (http://127.0.0.1:35203/game/__dev__/WAGame.js:2:94321)

    at <anonymous>:1:1

    at HTMLScriptElement.scriptLoaded (<anonymous>:18:21)

    at HTMLScriptElement.script.onload (<anonymous>:30:20)