Node.js mysql2 on AWS Lambda ERR_STREAM_WRITE_AFTER_END

Question

I have encountered a bizarre error using Node.js mysql2 library on AWS Lambda.

I am making a connection to a mysql database on AWS Aurora in my AWS Lambda function.

const conn = mysql.createConnection({
    host: '',
    port: 3306,
    user: '',
    password: '',
    database: ''
  })

  const query = util.promisify(conn.query).bind(conn)

I make a query

try {
  const result = await query(queryString)
  if (result && result.length > 0) {
    id = result[0].id
  }
} catch (error) {
  console.log('ERROR: query error')
  console.log(error)
}

This has always worked just fine.

This particular AWS Lambda function is called by a webhook through API Gateway.

Only when the webhook calls the function do I get this error saying that the mysql connection was closed before the query.

There is no point before the query whatsoever where the connection.end() or connection.close() is called.

The function gets past the query just fine when called from PostMan with the identical body that the webhook is passing. The connection is not closed!

Is there something in the AWS Lamba event from API Gateway that could possibly be causing the connection to die? Why is would node.js mysql2 throw this error only in the case of the webhook request?

To complete AWS Lambda log error is:

ERROR   Uncaught Exception  
{
    "errorType": "Error",
    "errorMessage": "write after end",
    "code": "ERR_STREAM_WRITE_AFTER_END",
    "fatal": true,
    "stack": [
        "Error [ERR_STREAM_WRITE_AFTER_END]: write after end",
        "    at writeAfterEnd (_stream_writable.js:266:14)",
        "    at Socket.Writable.write (_stream_writable.js:315:5)",
        "    at Connection.write (/var/task/node_modules/mysql2/lib/connection.js:217:17)",
        "    at Connection.writePacket (/var/task/node_modules/mysql2/lib/connection.js:262:12)",
        "    at ClientHandshake.sendCredentials (/var/task/node_modules/mysql2/lib/commands/client_handshake.js:63:16)",
        "    at ClientHandshake.handshakeInit (/var/task/node_modules/mysql2/lib/commands/client_handshake.js:136:12)",
        "    at ClientHandshake.execute (/var/task/node_modules/mysql2/lib/commands/command.js:39:22)",
        "    at Connection.handlePacket (/var/task/node_modules/mysql2/lib/connection.js:408:32)",
        "    at PacketParser.onPacket (/var/task/node_modules/mysql2/lib/connection.js:70:12)",
        "    at PacketParser.executeStart (/var/task/node_modules/mysql2/lib/packet_parser.js:75:16)"
    ]
}

To add to this, the query is inside a try catch block yet AWS Lambda says "Uncaught Exception"

Thanks for any help, Alex