不能连接云函数

• 当前 Bug 的表现（可附上截图）

• 预期表现

• 复现路径

• 提供一个最简复现 Demo

Error: errCode: -404011 cloud function execution error | errMsg: cloud.callFunction:fail requestID 87882a65-5ae1-11e9-82c9-525400e8849e, cloud function service error code -504002, error message wx is not defined; at cloud.callFunction api; 

    at new e (WAService.js:1)

    at u (WAService.js:1)

    at Object.t.returnAsFinalCloudSDKError (WAService.js:1)

    at Function.success (WAService.js:1)

    at WAService.js:1

    at T (WAService.js:1)

    at Le.<anonymous> (WAService.js:1)

    at Le.emit (WAService.js:1)

    at Ga (WAService.js:1)

    at WAService.js:1