Example:

`event.errorCode = -118`
`event.errorDescription = "CONNECTION_TIMED_OUT"`

or to be ISO with Google Chrome:
`event.errorDescription = "ERR_CONNECTION_TIMED_OUT"`

_See https://src.chromium.org/svn/trunk/src/net/base/net_error_list.h_

Would that make sense?

atom/renderer/atom_renderer_client.cc
#include "content/public/renderer/render_thread.h"
#include "content/public/renderer/render_view.h"
#include "ipc/ipc_message_macros.h"
#include "third_party/WebKit/public/web/WebCustomElement.h"
#include "third_party/WebKit/public/web/WebFrameWidget.h"
#include "third_party/WebKit/public/web/WebLocalFrame.h"
#include "third_party/WebKit/public/web/WebPluginParams.h"
#include "third_party/WebKit/public/web/WebKit.h"
#include "third_party/WebKit/public/web/WebScriptSource.h"
#include "third_party/WebKit/public/web/WebSecurityPolicy.h"
#include "third_party/WebKit/public/web/WebRuntimeFeatures.h"
#include "third_party/WebKit/public/web/WebView.h"
#if defined(OS_MACOSX)
#include "base/mac/mac_util.h"
#include "base/strings/sys_string_conversions.h"
#endif
#if defined(OS_WIN)
#include <shlobj.h>
#endif
namespace atom {
namespace {
class AtomRenderFrameObserver : public content::RenderFrameObserver {
 public:
  AtomRenderFrameObserver(content::RenderFrame* frame,
                          AtomRendererClient* renderer_client)
      : content::RenderFrameObserver(frame),
        world_id_(-1),
        renderer_client_(renderer_client) {}
  
  void DidCreateScriptContext(v8::Handle<v8::Context> context,