云开发-Cannot find module 'wx-js-utils'

求教：

小程序云开发微信支付云函数执行报错：

2019-05-26T11:08:02.442Z  { Error: errCode: -504002 functions execute fail | errMsg: callFunction:fail requestID 87555f74-7fa6-11e9-bd5f-5254005d5fdb, Cannot find module 'wx-js-utils'; at callFunction api;

at new CloudSDKError (/var/user/node_modules/wx-server-sdk/index.js:6172:28)

at returnAsCloudSDKError (/var/user/node_modules/wx-server-sdk/index.js:6224:16)

at Object.returnAsFinalCloudSDKError (/var/user/node_modules/wx-server-sdk/index.js:6238:13)

at Cloud.<anonymous> (/var/user/node_modules/wx-server-sdk/index.js:1787:41)

at step (/var/user/node_modules/tslib/tslib.js:133:27)

at Object.throw (/var/user/node_modules/tslib/tslib.js:114:57)

at rejected (/var/user/node_modules/tslib/tslib.js:105:69)

at <anonymous>

at process._tickCallback (internal/process/next_tick.js:188:7)

errCode: -504002,

errMsg: 'callFunction:fail requestID 87555f74-7fa6-11e9-bd5f-5254005d5fdb, Cannot find module \'wx-js-utils\'; at callFunction api; ',

requestID: undefined }

多数支付还是是可以的。少数报错，不知道什么原因。支付代码基本上是参考这个：

https://github.com/TencentCloudBase/tcb-demo-basic

看上去是wx-server-sdk找不到wx-js-utils。实在不知道是什么原因。

本地已经运行过npm install，上传云函数时也选择的是“云端安装依赖”。

哪位大神能伸手援助一下？先谢过！！