运行pm2 start app.js -i max报错Converting circular structure to JSON

{ online: true, success: true, pid: 14744 }

/usr/local/lib/node_modules/pm2/node_modules/axon/lib/sockets/sock.js:122

  msg.write(codec.encode(data[i]), codec.id);

                  ^

TypeError: Converting circular structure to JSON

at Object.stringify [as encode] (native)

at RepSocket.Socket.pack  (/usr/local/lib/node_modules/pm2/node_modules/axon/lib/sockets/sock.js:122:23)

at reply (/usr/local/lib/node_modules/pm2/node_modules/axon/lib/sockets/rep.js:60:25)

at Server.onmessage (/usr/local/lib/node_modules/pm2/node_modules/axon-rpc/lib/server.js:91:5)

at ex (/usr/local/lib/node_modules/pm2/lib/God.js:208:32)

at God.prepare (/usr/local/lib/node_modules/pm2/lib/God.js:214:16)

at God.executeApp (/usr/local/lib/node_modules/pm2/lib/God.js:183:15)

at Worker.module.exports.God.nodeApp  (/usr/local/lib/node_modules/pm2/lib/God/ClusterMode.js:68:22)

at Worker.g (events.js:185:14)

at Worker.EventEmitter.emit (events.js:85:17)