Fix an issue where the browser throws an exception on responseXML

When trying to use the XHR api set with a content type of 'text' the
browser throws an error it is unable to read responseXML as the response
isn't valid xml and the response type is not an empty string or
'document' as according to spec.

this change was implemented due to inconsistent implementation across
browsers and 3rd party network libraries which do parse xml responses
even when the response type is not set according to the spec.

In order to support all clients we now try to assign the responseXML
property when possible but fail silently when we cannot.

This will keep both behaviors consistent as incorrectly implemented
clients will be able to read the XML response while still supporting the
correctly implemented clients to not fail the request when trying to
access responseXML on an invalid request.

please see issues #86 #89 for more information.

dist/xhook.js

@@ -1,6 +1,6 @@
 // XHook - v1.4.8 - https://github.com/jpillora/xhook
 // Jaime Pillora <[email protected]> - MIT Copyright 2018
-(function(undefined) {
+(function(window,undefined) {
 var AFTER, BEFORE, COMMON_EVENTS, EventEmitter, FETCH, FIRE, FormData, NativeFetch, NativeFormData, NativeXMLHttp, OFF, ON, READY_STATE, UPLOAD_EVENTS, WINDOW, XHookFetchRequest, XHookFormData, XHookHttpRequest, XMLHTTP, convertHeaders, depricatedProp, document, fakeEvent, mergeObjects, msie, nullify, proxyEvents, slice, useragent, xhook, _base,
   __indexOf = [].indexOf || function(item) { for (var i = 0, l = this.length; i < l; i++) { if (i in this && this[i] === item) return i; } return -1; };
 
@@ -333,7 +333,11 @@ XHookHttpRequest = WINDOW[XMLHTTP] = function() {
     if (!xhr.responseType || xhr.responseType === "text") {
       response.text = xhr.responseText;
       response.data = xhr.responseText;
-      response.xml = xhr.responseXML;
+      try {
+        response.xml = xhr.responseXML;
+      } catch (_error) {
+
+      }
     } else if (xhr.responseType === "document") {
       response.xml = xhr.responseXML;
       response.data = xhr.responseXML;
@@ -693,4 +697,4 @@ if (typeof define === "function" && define.amd) {
   WINDOW.xhook = xhook;
 }
 
-}.call(this));
+}.call(this,window));

src/xhook.coffee

@@ -242,7 +242,13 @@ XHookHttpRequest = WINDOW[XMLHTTP] = ->
     if !xhr.responseType or xhr.responseType is "text"
       response.text = xhr.responseText
       response.data = xhr.responseText
-      response.xml = xhr.responseXML
+      try
+        response.xml = xhr.responseXML
+      catch
+        # unable to set responseXML due to response type, we attempt to assign responseXML
+        # when the type is text even though it's against the spec due to several libraries
+        # and browser vendors who allow this behavior. causing these requests to fail when
+        # xhook is installed on a page.
     else if xhr.responseType is "document"
       response.xml = xhr.responseXML
       response.data = xhr.responseXML