stringifying xhr error response

request/request.js

@@ -3,13 +3,13 @@
 var buildPathname = require("../pathname/build")
 var hasOwn = require("../util/hasOwn")
 
-module.exports = function($window, oncompletion) {
+module.exports = function ($window, oncompletion) {
 	function PromiseProxy(executor) {
 		return new Promise(executor)
 	}
 
 	function makeRequest(url, args) {
-		return new Promise(function(resolve, reject) {
+		return new Promise(function (resolve, reject) {
 			url = buildPathname(url, args.params)
 			var method = args.method != null ? args.method.toUpperCase() : "GET"
 			var body = args.body
@@ -20,7 +20,7 @@ module.exports = function($window, oncompletion) {
 			var original = xhr, replacedAbort
 			var abort = xhr.abort
 
-			xhr.abort = function() {
+			xhr.abort = function () {
 				aborted = true
 				abort.call(this)
 			}
@@ -43,7 +43,7 @@ module.exports = function($window, oncompletion) {
 				}
 			}
 
-			xhr.onreadystatechange = function(ev) {
+			xhr.onreadystatechange = function (ev) {
 				// Don't throw errors on xhr.abort().
 				if (aborted) return
 
@@ -93,9 +93,9 @@ module.exports = function($window, oncompletion) {
 							resolve(response)
 						}
 						else {
-							var completeErrorResponse = function() {
+							var completeErrorResponse = function () {
 								try { message = ev.target.responseText }
-								catch (e) { message = response }
+								catch (e) { message = JSON.stringify(response) }
 								var error = new Error(message)
 								error.code = ev.target.status
 								error.response = response
@@ -107,7 +107,7 @@ module.exports = function($window, oncompletion) {
 								// This allows `xhr.ontimeout` to run in the case that there is a timeout
 								// Without this setTimeout, `xhr.ontimeout` doesn't have a chance to reject
 								// as `xhr.onreadystatechange` will run before it
-								setTimeout(function() {
+								setTimeout(function () {
 									if (isTimeout) return
 									completeErrorResponse()
 								})
@@ -133,7 +133,7 @@ module.exports = function($window, oncompletion) {
 				// Propagate the `abort` to any replacement XHR as well.
 				if (xhr !== original) {
 					replacedAbort = xhr.abort
-					xhr.abort = function() {
+					xhr.abort = function () {
 						aborted = true
 						replacedAbort.call(this)
 					}
@@ -161,7 +161,7 @@ module.exports = function($window, oncompletion) {
 	}
 
 	return {
-		request: function(url, args) {
+		request: function (url, args) {
 			if (typeof url !== "string") { args = url; url = url.url }
 			else if (args == null) args = {}
 			var promise = makeRequest(url, args)
@@ -183,10 +183,10 @@ module.exports = function($window, oncompletion) {
 				// corresponding comment in `request/tests/test-request.js` for
 				// a bit more background on the issue at hand.
 				promise.constructor = PromiseProxy
-				promise.then = function() {
+				promise.then = function () {
 					count++
 					var next = then.apply(promise, arguments)
-					next.then(complete, function(e) {
+					next.then(complete, function (e) {
 						complete()
 						if (count === 0) throw e
 					})