var errorHandler = require('request-error-handler')
var express = require('express')
var app = module.exports = express()
function responder (req, res, error, stack) { /* Custom respond logic here */ }
var defaultLanguage = 'en'
var customMessages = {}
app.use(errorHandler(responder, defaultLanguage, customMessages))

interface CustomMessages {
  [type: string]: {
    [keyword: string]: {
      [language: string]: (error: RequestError) => string
    }
  }
}

interface RequestError {
  type: 'json' | 'form' | 'headers' | 'query' | 'xml' | string /* Comes with standard types built-in, but you can also provide your own */
  keyword: string /* Keyword that failed validation */
  message: string /* Merged with i18n when available */
  id?: string /* A unique identifier for the instance of this error */
  dataPath?: string /* Natural path to the error message (E.g. JSON Pointers when using JSON) */
  data?: any /* The data that failed validation */
  schema?: any /* The schema value that failed validation */
  detail?: string /* Additional details about this specific error instance */
  meta?: { [name: string]: string } /* Meta data from the error (XML validation provides a code, column, etc.) */
}