I am trying to deploy my lambda function via Serverless framework’s sls deploy command. The deployment goes smoothly but when the lambda runs I get the following error.

{
    "errorType": "Runtime.ImportModuleError",
    "errorMessage": "Error: Cannot find module 'lambda'nRequire stack:n- /var/runtime/index.mjs",
    "stack": [
        "Runtime.ImportModuleError: Error: Cannot find module 'lambda'",
        "Require stack:",
        "- /var/runtime/index.mjs",
        "    at _loadUserApp (file:///var/runtime/index.mjs:1087:17)",
        "    at async UserFunction.js.module.exports.load (file:///var/runtime/index.mjs:1119:21)",
        "    at async start (file:///var/runtime/index.mjs:1282:23)",
        "    at async file:///var/runtime/index.mjs:1288:1"
    ]
}

I do not have any index.mjs file in my src or build folder so I am not sure what the next steps are to fix this. I went through few similarly asked questions here and other places but none of those solutions actually worked for me.

My project folder structure

My Serverless.yml file

service: api-gateway-websocket-poc
frameworkVersion: '3'

provider:
  name: aws
  runtime: nodejs18.x
  stage: ${opt:stage, 'dev'}
  region: ${opt:region, 'us-east-2'}
  websocketsApiName: api-gateway-ws-poc-${self:provider.stage}
  websocketsApiRouteSelectionExpression: $request.body.action
  websocketsDescription: API Gateway WS POC
  iamRoleStatements:
    - Effect: Allow
      Action:
        - "execute-api:ManageConnections"
      Resource:
        - "arn:aws:execute-api:*:*:**/@connections/*"

functions:
  connectionHandler:
    handler: src/lambda.handler
    events:
      - websocket:
          route: $connect
      - websocket:
          route: $disconnect
  defaultHandler:
    handler: src/lambda.handler
    events:
      - websocket:
          route: $default
  actionHandler:
    handler: src/lambda.handler
    events:
      - websocket:
          route: myAction

My lambda.ts file

import * as AWS from 'aws-sdk';
import { APIGatewayProxyHandler, APIGatewayProxyResult } from "aws-lambda";
  
export const handler: APIGatewayProxyHandler = async (
  event,
  context,
  callback
): Promise<APIGatewayProxyResult> => {
  
  console.log("on send message", event.requestContext.connectionId, event.requestContext.routeKey, event.body);

  const {
    routeKey,
    connectionId,
    domainName,
    stage
  } = event.requestContext;

  
  return { statusCode: 200, body: 'Data sent.' };
};

My tsconfig.json

{
  "compilerOptions": {
    "composite": true,                                /* Enable constraints that allow a TypeScript project to be used with project references. */
    "target": "es2016",                                  /* Set the JavaScript language version for emitted JavaScript and include compatible library declarations. */
    "module": "commonjs",                                /* Specify what module code is generated. */
    "rootDir": "./src",                                  /* Specify the root folder within your source files. */
    "allowJs": true,                                  /* Allow JavaScript files to be a part of your program. Use the 'checkJS' option to get errors from these files. */
    "outDir": "./build",                                   /* Specify an output folder for all emitted files. */
    "esModuleInterop": true,                             /* Emit additional JavaScript to ease support for importing CommonJS modules. This enables 'allowSyntheticDefaultImports' for type compatibility. */
    "forceConsistentCasingInFileNames": true,            /* Ensure that casing is correct in imports. */
    "strict": true,                                      /* Enable all strict type-checking options. */
    "skipLibCheck": true                                 /* Skip type checking all .d.ts files. */
  }
}

Package.json

{
  "name": "api-gateway-websocket-poc",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "dev": "nodemon src/app.ts",
    "start": "tsc && node build/app",
    "build": "npm run clearBuild && npm run tsc",
    "clearBuild": "npm run rimraf -- build",
    "rimraf": "rimraf",
    "tsc": "tsc"
  },
  "dependencies": {
    "express": "^4.18.2",
    "serverless-http": "^3.1.1"
  },
  "devDependencies": {
    "@types/aws-lambda": "^8.10.137",
    "@types/express": "^4.17.21",
    "@types/node": "^20.12.11",
    "aws-sdk": "^2.1617.0",
    "nodemon": "^3.1.0",
    "rimraf": "^5.0.5",
    "serverless": "^3.38.0",
    "ts-node": "^10.9.2",
    "typescript": "^5.4.5"
  }
}

I am deploying this from my local machine by simple doing
SLS_DEBUG=* serverless deploy --stage dev --region us-east-2

I am trying to understand from where the index.mjs file is suppose to come from, or whether I need to change my own pattern before deploying to AWS.