Gtk::IconThemeError with astroid

[Sepp Tannhuber <sepp tannhuber yahoo de>]

I'm trying to run astroid from https://github.com/gauteh/astroid.
Unfortunately it crashes, saying:

(astroid:21564): Gtk-WARNING **: Could not find the icon 'mail-send-symbolic'. The 'hicolor' theme

was not found either, perhaps you need to install it.
You can get a copy from:
 http://icon-theme.freedesktop.org/releases
terminate called after throwing an instance of 'Gtk::IconThemeError'
Aborted

I also ran the application with strace. There are many weird path names in lines saying
»No such file or directory«. The output is at
https://gist.github.com/tannhuber/c7cae862f897efccd3cb.

Can anybody help me to find out what's going wrong there?