this is error info, Look at the buffer error in the code, but I don't know where the source is

enter image description here

    TypeError [ERR_INVALID_ARG_TYPE]: The first argument must be of type string or an instance of Buffer, ArrayBuffer, or Array or an Array-like Object. Received undefined
        at Function.from (buffer.js:331:9)
        at ContextCarrier._this.decode (/app/v7-mopower/node_modules/skywalking-backend-js/src/trace/context/ContextCarrier.ts:43:19)
        at ContextCarrier.set (/app/v7-mopower/node_modules/skywalking-backend-js/src/trace/context/ContextCarrier.ts:61:32)
        at /app/v7-mopower/node_modules/skywalking-backend-js/src/trace/context/ContextCarrier.ts:88:95
        at Array.forEach (<anonymous>)
        at Function.ContextCarrier.from (/app/v7-mopower/node_modules/skywalking-backend-js/src/trace/context/ContextCarrier.ts:88:66) 
        at Server._sw_request (/app/v7-mopower/node_modules/skywalking-backend-js/src/plugins/HttpPlugin.ts:151:40)
        at Server.emit (events.js:315:20)
        at Server.<anonymous> (/usr/local/lib/node_modules/pm2/node_modules/@pm2/io/src/metrics/httpMetrics.ts:181:25)
        at parserOnIncoming (_http_server.js:790:12)
        at HTTPParser.parserOnHeadersComplete (_http_common.js:119:17)

this is startd code

import agent from 'skywalking-backend-js';

export class M7Skywalking {
  static tryLoad(serviceName: string) {
    if (!process.env.SW_AGENT_NAME || !serviceName) {
      return;
    }
    agent.start();
  }
}