Trying to call an external api with aws lamda returning error type object

Question

This is my code in which i am trying to call an external api with aws lambda.

const http = require('http');
exports.handler = async (event) => {
    let dataString = '';
    const options = {
      host: 'host',
      path: '/v1/endpoint',
      method: 'POST',
      headers: {
        'Content-Type': 'application/json'
      }
    };    
    const response = await new Promise((resolve, reject) => {
        const req = http.request(options, function(res) {
        res.on('data', chunk => {
            dataString += chunk;
        });
        res.on('end', () => {
            resolve({
                statusCode: 200,
                body: JSON.stringify(JSON.parse(dataString), null, 4)
            });
          });
        });
        
        req.on('error', (e) => {
          reject({
              statusCode: 500,
              body: 'Something went wrong!'
          });
        });
    });
    
    return JSON.stringify(response);
};

But what I am getting in response is as follows.

Test Event Name test1

Response { "errorType": "object", "errorMessage": "[object Object]", "trace": [] }

Function Logs START RequestId: c9701afa-9bc5-4750-8e10-5558d5e3e342 Version: $LATEST 2022-03-03T07:23:07.844Z c9701afa-9bc5-4750-8e10-5558d5e3e342 ERROR Invoke Error {"errorType":"Error","errorMessage":"[object Object]","stack":["Error: [object Object]"," at _homogeneousError (/var/runtime/CallbackContext.js:12:12)"," at postError (/var/runtime/CallbackContext.js:29:54)"," at done (/var/runtime/CallbackContext.js:58:7)"," at fail (/var/runtime/CallbackContext.js:70:7)"," at /var/runtime/CallbackContext.js:106:16"," at processTicksAndRejections (internal/process/task_queues.js:95:5)"]} END RequestId: c9701afa-9bc5-4750-8e10-5558d5e3e342 REPORT RequestId: c9701afa-9bc5-4750-8e10-5558d5e3e342 Duration: 198.36 ms Billed Duration: 199 ms Memory Size: 128 MB Max Memory Used: 57 MB Init Duration: 156.11 ms

Request ID c9701afa-9bc5-4750-8e10-5558d5e3e342

How do i debug this?

Answer 1

Pass your "reject" error object to JSON.stringify and the nested error message object will be readable instead of just being [object Object] in the response.

I also suggest passing the actual error object along in the body, so that you can see from the response what has gone wrong:

 req.on('error', (e) => {
     reject(JSON.stringify({
         statusCode: 500,
         body: 'Something went wrong: ' + e
     }));
 });