从小程序云函数调用imgSecCheck()时一直报41005错误，但是对应的media已经按文档设置。

errCode: 41005  | errMsg: openapi.security.imgSecCheck:fail media data missing hint: [xKvxiA04673955]

错误信息提示

imgSecCheck() is triggered from cloud with event:  
{action: "imgSecCheck", contentType: "image/jpg", buffer: {…}}
action: "imgSecCheck"
buffer: {type: "Buffer", data: Array(15006)}
contentType: "image/jpg"
__proto__: Object
exception during imgSecCheck, e:  Error: errCode: 41005  | errMsg: openapi.security.imgSecCheck:fail media data missing hint: [xKvxiA04673955]
    at callWXOpenAPI (/.../cloudfunctions/openapi/node_modules/wx-server-sdk/index.js:2267:31)
    at processTicksAndRejections (internal/process/task_queues.js:85:5)
    at async imgSecCheck (/.../cloudfunctions/openapi/index.js:43:15)

小程序云开发服务端代码段

// 图片内容检测
async function imgSecCheck(event) {
  console.debug('imgSecCheck() is triggered from cloud with event: ', event)
  try {
    let res = await cloud.openapi.security.imgSecCheck({
      media: {
        contentType: event.contentType, // 'image/png',
        value: event.value, // Buffer
      }
    })
  
    return res
  }
  catch (e) {
    console.error('exception during imgSecCheck, e: ', e)
    return e
  }
}