@middy/http-error-handler/index.js

Http error handler middleware for the middy framework

import { jsonSafeParse, normalizeHttpResponse } from '@middy/util'

const defaults = {
  logger: console.error,
  fallbackMessage: undefined
}

const httpErrorHandlerMiddleware = (opts = {}) => {
  const options = { ...defaults, ...opts }

  const httpErrorHandlerMiddlewareOnError = async (request) => {
    if (request.response !== undefined) return
    if (typeof options.logger === 'function') {
      options.logger(request.error)
    }

    // Set default expose value, only passes in when there is an override
    if (request.error.statusCode && request.error.expose === undefined) {
      request.error.expose = request.error.statusCode < 500
    }

    // Non-http error OR expose set to false
    if (!request.error.expose || !request.error.statusCode) {
      request.error = {
        statusCode: 500,
        message: options.fallbackMessage,
        expose: true
      }
    }

    if (request.error.expose) {
      normalizeHttpResponse(request)
      const { statusCode, message, headers } = request.error

      request.response = {
        ...request.response,
        statusCode,
        headers: {
          ...request.response.headers,
          ...headers
        }
      }

      if (message) {
        const headerContentType =
          typeof jsonSafeParse(message) === 'string'
            ? 'text/plain'
            : 'application/json'
        request.response.body = message
        request.response.headers['Content-Type'] = headerContentType
      }
    }
  }

  return {
    onError: httpErrorHandlerMiddlewareOnError
  }
}
export default httpErrorHandlerMiddleware