nicer async stack traces

lib/request.js

@@ -1,14 +1,13 @@
 'use strict'
 
+let captureStackTrace = () => {}
+if (process.env.NODE_ENV === 'dev') {
+	captureStackTrace = require('capture-stack-trace')
+}
 const Promise = require('pinkie-promise')
 const {fetch} = require('fetch-ponyfill')({Promise})
 const {stringify} = require('query-string')
 
-const hafasError = (err) => {
-	err.isHafasError = true
-	return err
-}
-
 const request = (profile, data) => {
 	const body = profile.transformReqBody({lang: 'en', svcReqL: [data]})
 	const req = profile.transformReq({
@@ -24,20 +23,33 @@ const request = (profile, data) => {
 	})
 	const url = profile.endpoint + (req.query ? '?' + stringify(req.query) : '')
 
+	// Async stack traces are not supported everywhere yet, so we create our own.
+	const err = new Error()
+	err.isHafasError = true
+	err.request = body
+	captureStackTrace(err)
+
 	return fetch(url, req)
 	.then((res) => {
-		if (!res.ok) {
-			const err = new Error(res.statusText)
 		err.statusCode = res.status
-			throw hafasError(err)
+		if (!res.ok) {
+			err.message = res.statusText
+			throw err
 		}
 		return res.json()
 	})
 	.then((b) => {
-		if (b.err) throw hafasError(new Error(b.err))
-		if (!b.svcResL || !b.svcResL[0]) throw new Error('invalid response')
+		if (b.err) {
+			err.message = b.err
+			throw err
+		}
+		if (!b.svcResL || !b.svcResL[0]) {
+			err.message = 'invalid response'
+			throw err
+		}
 		if (b.svcResL[0].err !== 'OK') {
-			throw hafasError(new Error(b.svcResL[0].errTxt))
+			err.message = b.svcResL[0].errTxt
+			throw err
 		}
 		const d = b.svcResL[0].res
 		const c = d.common || {}

package.json

@@ -31,6 +31,7 @@
 		"node": ">=6"
 	},
 	"dependencies": {
+		"capture-stack-trace": "^1.0.0",
 		"fetch-ponyfill": "^4.1.0",
 		"lodash": "^4.17.4",
 		"luxon": "^0.3.1",
@@ -55,7 +56,7 @@
 		"vbb-stations-autocomplete": "^3.0.0"
 	},
 	"scripts": {
-		"test": "node test/index.js",
+		"test": "env NODE_ENV=dev node test/index.js",
 		"prepublishOnly": "npm test | tap-spec"
 	}
 }