yelp crashes on opening a new window from an empty or invalid page

[fbraun]

Steps to reproduce:

1) Execute in terminal: yelp http://www.example.com
2) Watch your browser start / open another tab. Disregard that
3) An empty yelp window starts
4) In that empty yelp window click on Page -> New Window
5) yelp crashes:
(yelp:25271): GLib-GObject-CRITICAL **: g_type_instance_get_private: assertion `instance != NULL && instance->g_class != NULL' failed
Segmentation fault

System specification:

Ubuntu: 12.04
yelp: 3.4.1-0ubuntu1
kernel: 3.2.0-29-generic x86_64