Running firebase cloud function fails with a SyntaxError

I am following all the steps presented in this link but it does not seem to be sending me anywhere thus I am asking for help here. I have a sample function that I want to first test and then deploy to firebase cloud function but its failing with this message:

HTTP/1.1 400 Bad Request x-powered-by: Express content-security-policy: default-src 'none' x-content-type-options: nosniff content-type: text/html; charset=utf-8 content-length: 1295 date: Mon, 27 Dec 2021 13:05:48 GMT connection: close

Error

SyntaxError: Unexpected token ' in JSON at
position 0
    at JSON.parse (<anonymous>)

   at createStrictSyntaxError
(C:\Users\janic\AppData\Roaming\npm\node_modules\firebase-tools\node_modules\body-parser\lib\types\json.js:158:10)

   at parse
(C:\Users\janic\AppData\Roaming\npm\node_modules\firebase-tools\node_modules\body-parser\lib\types\json.js:83:15)

   at
C:\Users\janic\AppData\Roaming\npm\node_modules\firebase-tools\node_modules\body-parser\lib\read.js:121:18

   at invokeCallback
(C:\Users\janic\AppData\Roaming\npm\node_modules\firebase-tools\node_modules\raw-body\index.js:224:16)

   at done
(C:\Users\janic\AppData\Roaming\npm\node_modules\firebase-tools\node_modules\raw-body\index.js:213:7)

   at IncomingMessage.onEnd
(C:\Users\janic\AppData\Roaming\npm\node_modules\firebase-tools\node_modules\raw-body\index.js:273:7)

   at IncomingMessage.emit (node:events:402:35)
  
 at endReadableNT (node:internal/streams/readable:1343:12)

   at processTicksAndRejections
(node:internal/process/task_queues:83:21)

I do not have any syntax error in the code, I literally copied the code from the link.

// functions/index.js
const functions = require('firebase-functions');
const faker = require('faker');

// Initialize products array
const products = [];

// Max number of products
const LIMIT = 100;

// Push a new product to the array
for (let i = 0; i < LIMIT; i++) {
   products.push({
      name: faker.commerce.productName(),
      price: faker.commerce.price(),
   });
}

exports.listProducts = functions.https.onCall((data, context) => {
   return products;
});

and I invoke it from the console using this command:

curl -i -H "Accept: application/json" -H "Content-Type: application/json" -X POST -d '{"data":{}}' http://localhost:5001/bleconnect/us-central1/listProducts

Edit:

The error indicates there is something wrong with the parsing, however, even after trying to return a simple string "Test", it still throws the same error.