const fileManager = wx.getFileSystemManager();
    try {
      fileManager.accessSync('/env.txt');//这个文件放在项目根目录下
      that.globalData.ENV = ENVS.DEV;
    } catch (e) {
      console.log(e)
      that.globalData.ENV = ENVS.PROD;
    }

报错
Error: accessSync:fail no such file or directory, access "/env.txt"
    at accessSync (VM663 WAService.js:1)
    at Object.e.<computed> [as accessSync] (VM663 WAService.js:1)
    at pe.onLaunch (app.js? [sm]:32)
    at pe.<anonymous> (VM663 WAService.js:1)
    at VM663 WAService.js:1
    at new pe (VM663 WAService.js:1)
    at Function.<anonymous> (VM663 WAService.js:1)
    at VM663 WAService.js:1
    at app.js? [sm]:12
    at require (VM663 WAService.js:1)