2019-04-16 process.on('unresolvedPromise')

0.js

// in index.js

...

async function handler(event, context) {
  try {
    return handlerService.call(event, context, { AWS })
  } catch (e) {
    if (process.env.NODE_ENV === 'local') throw e
    throw JSON.stringify(e)
  }
}

// process.on('unresolvedPromise', err => {
//   console.error(err.toString())
//   process.exit(1)
// })

exports.handler = handler

// handlerServices.js

...
async function call(event, context, options) {
  throw new Error('test')
  if (!options.AWS) {
    throw new Error('Please pass your AWS instance via the "AWS" option.')
  }
 
...

// lambda input is irrelevant since we throw on first line

// result:

{
  "errorMessage": "test",
  "errorType": "Error",
  "stackTrace": [
    "Object.call (/var/task/handlers/handlerService.js:7:9)",
    "handler (/var/task/index.js:8:27)"
  ]
}