项目导入了tensorflow.js，在app.js 设置了以下代码

//app.js
var fetchWechat = require('fetch-wechat');
var tf = require('@tensorflow/tfjs-core');
var webgl = require('@tensorflow/tfjs-backend-webgl');
var plugin = requirePlugin('tfjsPlugin');
App({
  onLaunch() {
    plugin.configPlugin({
      // polyfill fetch function
      fetchFunc: fetchWechat.fetchFunc(),
      // inject tfjs runtime
      tf,
      // inject webgl backend
      webgl,
      // provide webgl canvas
      canvas: wx.createOffscreenCanvas()
    });
    tf.tensor([1, 2, 3, 4]).print()
  } 
})

//index.js
Page({ 
  onLoad() {
     const camera = wx.createCameraContext(this)
     let count = 0
     const listener = camera.onCameraFrame(frame=>{
        count++
        if(count===4) {
          console.log(frame)
          count = 0
        }
     })
     listener.start()
  },  
})

由于在开发者工具模式下没法打开camera（不知道为啥不支持，真麻烦），于是按提示开启真机调试，但是却发生了以下错误，请官方人员帮忙查看，感谢

(unknown) SystemError (appServiceSDKScriptError)
Cannot read property 'createOffscreenCanvas' of undefined
TypeError: Cannot read property 'createOffscreenCanvas' of undefined
    at eval (eval at n.call.document (http://127.0.0.1:45717/remote-debug/runtime.js?devtools_ignore=true:1:13107), <anonymous>:2:2104670)
    at a (eval at n.call.document (http://127.0.0.1:45717/remote-debug/runtime.js?devtools_ignore=true:1:13107), <anonymous>:2:2105306)
    at Object.n (eval at n.call.document (http://127.0.0.1:45717/remote-debug/runtime.js?devtools_ignore=true:1:13107), <anonymous>:2:2104139)
    at Object.l.<computed> (eval at n.call.document (http://127.0.0.1:45717/remote-debug/runtime.js?devtools_ignore=true:1:13107), <anonymous>:2:2101353)
    at Object.eval (eval at n.call.document (http://127.0.0.1:45717/remote-debug/runtime.js?devtools_ignore=true:1:13107), <anonymous>:2:1780471)
    at Object.eval (eval at n.call.document (http://127.0.0.1:45717/remote-debug/runtime.js?devtools_ignore=true:1:13107), <anonymous>:2:3258311)
    at < at wx.createOffscreenCanvas>
    at Object.eval (eval at n.call.document (http://127.0.0.1:45717/remote-debug/runtime.js?devtools_ignore=true:1:13107), <anonymous>:2:122632)
    at wA.onLaunch (weapp:///app.js:18:18)
    at wA.eval (eval at n.call.document (http://127.0.0.1:45717/remote-debug/runtime.js?devtools_ignore=true:1:13107), <anonymous>:2:3575772)
errorReport
(unknown) MiniProgramError
Cannot assign to read only property 'btoa' of object '[object Window]'
TypeError: Cannot assign to read only property 'btoa' of object '[object Window]'
    at e ([__wxPluginCode__]:1116:45)
    at Object.exports.setupWechatPlatform ([__wxPluginCode__]:1116:1599)
    at Object.exports.configPlugin ([__wxPluginCode__]:1072:148)
    at wA.onLaunch (weapp:///app.js:10:12)
    at wA.eval (eval at n.call.document (http://127.0.0.1:45717/remote-debug/runtime.js?devtools_ignore=true:1:13107), <anonymous>:2:3575772)
    at new wA (eval at n.call.document (http://127.0.0.1:45717/remote-debug/runtime.js?devtools_ignore=true:1:13107), <anonymous>:2:3576529)
    at Function.eval (eval at n.call.document (http://127.0.0.1:45717/remote-debug/runtime.js?devtools_ignore=true:1:13107), <anonymous>:2:3576841)
    at eval (eval at n.call.document (http://127.0.0.1:45717/remote-debug/runtime.js?devtools_ignore=true:1:13107), <anonymous>:2:3563396)
    at eval (weapp:///app.js:8:1)
    at require (eval at n.call.document (http://127.0.0.1:45717/remote-debug/runtime.js?devtools_ignore=true:1:13107), <anonymous>:2:3619027)