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http-error-handler

Automatically handles uncaught errors that contain the properties statusCode (number) and message (string) and creates a proper HTTP response for them (using the message and the status code provided by the error object). Additionally, support for the property expose is included with a default value of statusCode < 500. We recommend generating these HTTP errors with the npm module http-errors. When manually catching and setting errors with statusCode >= 500 setting {expose: true} is needed for them to be handled.

This middleware should be set as the last error handler attached, first to execute. When non-http errors (those without statusCode) occur they will be returned with a 500 status code.

Install​

To install this middleware you can use NPM:

npm install --save @middy/http-error-handler

Options​

  • logger (defaults to console.error) - a logging function that is invoked with the current error as an argument. You can pass false if you don't want the logging to happen.
  • fallbackMessage (default undefined) - When non-http errors (those without statusCode) occur you can set a fallback message to be used. These will be returned with a 500 status code.

Sample usage​

import middy from '@middy/core'
import httpErrorHandler from '@middy/http-error-handler'
import createError from 'http-errors'

const lambdaHandler = (event, context) => {
  throw new createError.UnprocessableEntity()
}
export const handler = middy().use(httpErrorHandler()).handler(lambdaHandler)

// when Lambda runs the handler...
handler({}, {}, (_, response) => {
  deepEqual(response, {
    statusCode: 422,
    body: 'Unprocessable Entity'
  })
})