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.h
void WebKitInitialized() override;
  
  void RenderThreadStarted() override;
  void RenderFrameCreated(content::RenderFrame*) override;
  void RenderViewCreated(content::RenderView*) override;
  void RunScriptsAtDocumentStart(content::RenderFrame* render_frame) override;
  blink::WebSpeechSynthesizer* OverrideSpeechSynthesizer(
      blink::WebSpeechSynthesizerClient* client) override;
  bool OverrideCreatePlugin(content::RenderFrame* render_frame,
                            blink::WebLocalFrame* frame,
                            const blink::WebPluginParams& params,
                            blink::WebPlugin** plugin) override;
  bool ShouldFork(blink::WebLocalFrame* frame,
                  const GURL& url,
                  const std::string& http_method,
                  bool is_initial_navigation,
                  bool is_server_redirect,
                  bool* send_referrer) override;
  content::BrowserPluginDelegate* CreateBrowserPluginDelegate(
      content::RenderFrame* render_frame,
      const std::string& mime_type,
      const GURL& original_url) override;
  void AddKeySystems(std::vector<media::KeySystemInfo>* key_systems) override;
  scoped_ptr<NodeBindings> node_bindings_;
  scoped_ptr<AtomBindings> atom_bindings_;
  DISALLOW_COPY_AND_ASSIGN(AtomRendererClient);
};
}  
#endif