我在local端 call 雲函數調用database代碼在一開始會報錯

const cloud = require('wx-server-sdk')

cloud.init()

const db = cloud.database() // 讀到這行會報錯

Error: errCode: -404011 cloud function execution error | errMsg: cloud.callFunction:fail cloud function service error code -504002, error message TypeError: this.realHandler is not a function

    at EventHandler.handle (/var/runtime/node8/bootstrap.js:238:34)

    at invoke (/var/runtime/node8/bootstrap.js:111:22)

    at Timeout.setTimeout [as _onTimeout] (/var/runtime/node8/bootstrap.js:61:9)

    at ontimeout (timers.js:475:11)

    at tryOnTimeout (timers.js:310:5)

    .

    .

    .

請問有人知道是什麼原因嗎