Add response text to HTTP errors

Requested in #319

Change-Id: I2f52519d7a45769a0d2db3c038c9c04cf7fb59c1

Author: joeyparrish

lib/net/http_plugin.js

@@ -59,16 +59,18 @@ shaka.net.HttpPlugin = function(uri, request) {
         var response = {uri: uri, data: target.response, headers: headers};
         resolve(response);
       } else {
-        if (!COMPILED) {
-          var responseText =
-              shaka.util.StringUtils.fromBytesAutoDetect(target.response);
-          shaka.log.debug('HTTP error text:', responseText);
-        }
+        var responseText = null;
+        try {
+          responseText = shaka.util.StringUtils.fromBytesAutoDetect(
+              target.response);
+        } catch (exception) {}
+        shaka.log.debug('HTTP error text:', responseText);
         reject(new shaka.util.Error(
             shaka.util.Error.Category.NETWORK,
             shaka.util.Error.Code.BAD_HTTP_STATUS,
             uri,
-            target.status));
+            target.status,
+            responseText));
       }
     };
     xhr.onerror = function(event) {

lib/util/error.js

@@ -135,6 +135,8 @@ shaka.util.Error.Code = {
    * An HTTP network request returned an HTTP status that indicated a failure.
    * <br> error.data[0] is the URI.
    * <br> error.data[1] is the status code.
+   * <br> error.data[2] is the response text, or null if the response could not
+   *   be interpretted as text.
    */
   'BAD_HTTP_STATUS': 1001,