I’m trying to build a Slack Bot using the @slack/bolt node.js library on AWS Lambda
I followed the instructions on Slack documentation, but I’m having trouble with the AWSLambdaReceiver (I guess)

I created the project using SAM with the Hello-World template
This is my app.mjs

import pkg from '@slack/bolt';
const { App, AwsLambdaReceiver } = pkg;

const awsLambdaReceiver = new AwsLambdaReceiver({
    signingSecret: MY_SIGNING_SECRET
});


const app = new App({
  token: MY_TOKEN,
  receiver: awsLambdaReceiver,
});

// Listens to incoming messages that contain "hello"
app.message('hello', async ({ message, say }) => {
  // say() sends a message to the channel where the event was triggered
  await say({
    blocks: [
      {
        "type": "section",
        "text": {
          "type": "mrkdwn",
          "text": `Hey there <@${message.user}>!`
        },
        "accessory": {
          "type": "button",
          "text": {
            "type": "plain_text",
            "text": "Click Me"
          },
          "action_id": "button_click"
        }
      }
    ],
    text: `Hey there <@${message.user}>!`
  });
});

app.action('button_click', async ({ body, ack, say }) => {
  // Acknowledge the action
  await ack();
  await say(`<@${body.user.id}> clicked the button`);
});

export const lambdaHandler = async (event, context, callback) => {
    const handler = await awsLambdaReceiver.start();
    return handler(event, context, callback);
}

This is my template.yaml file

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: >
  slack-bot-lambda

  Sample SAM Template for slack-bot-lambda
  
# More info about Globals: https://github.com/awslabs/serverless-application-model/blob/master/docs/globals.rst
Globals:
  Function:
    Timeout: 3

Resources:
  HelloWorldFunction:
    Type: AWS::Serverless::Function # More info about Function Resource: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#awsserverlessfunction
    Properties:
      CodeUri: hello-world/
      Handler: app.lambdaHandler
      Runtime: nodejs18.x
      Architectures:
        - x86_64
      Events:
        HelloWorld:
          Type: Api # More info about API Event Source: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#api
          Properties:
            Path: /hello/slack/events
            Method: post

Outputs:
  # ServerlessRestApi is an implicit API created out of Events key under Serverless::Function
  # Find out more about other implicit resources you can reference within SAM
  # https://github.com/awslabs/serverless-application-model/blob/master/docs/internals/generated_resources.rst#api
  HelloWorldApi:
    Description: "API Gateway endpoint URL for Prod stage for Hello World function"
    Value: !Sub "https://${ServerlessRestApi}.execute-api.${AWS::Region}.amazonaws.com/Prod/hello/"
  HelloWorldFunction:
    Description: "Hello World Lambda Function ARN"
    Value: !GetAtt HelloWorldFunction.Arn
  HelloWorldFunctionIamRole:
    Description: "Implicit IAM Role created for Hello World function"
    Value: !GetAtt HelloWorldFunctionRole.Ar

The error I’m getting on AWS Lambda when I try to run is:

{
  "errorType": "TypeError",
  "errorMessage": "Wrong arguments",
  "trace": [
    "TypeError: Wrong arguments",
    "    at RAPIDClient.postInvocationResponse (file:///var/runtime/index.mjs:434:27)",
    "    at complete (file:///var/runtime/index.mjs:811:16)",
    "    at done (file:///var/runtime/index.mjs:835:11)",
    "    at succeed (file:///var/runtime/index.mjs:839:9)",
    "    at file:///var/runtime/index.mjs:872:20"
  ]
}

And

{"errorType":"Runtime.UnhandledPromiseRejection","errorMessage":"TypeError: Cannot convert undefined or null to object","reason":{"errorType":"TypeError","errorMessage":"Cannot convert undefined or null to object","stack":["TypeError: Cannot convert undefined or null to object","    at Function.keys (<anonymous>)","    at AwsLambdaReceiver.getHeaderValue (/var/task/node_modules/@slack/bolt/dist/receivers/AwsLambdaReceiver.js:186:43)"

I’m assuming the error is on the return handler(event, context, callback) but I don’t know much I could do.

Appreciate your help. Thanks!

I tried checking if any of the handler parameters was null, but apparently none of them were null