Traceback (most recent call last):
  File "/usr/share/software-center/softwarecenter/app.py", line 539, in on_application_request_action
    self.db, self.icons):
  File "/usr/share/software-center/softwarecenter/view/dependency_dialogs.py", line 51, in confirm_install
    return _confirm_remove_internal(parent, datadir, app, db, icons, primary, button_text, depends, cache)
  File "/usr/share/software-center/softwarecenter/view/dependency_dialogs.py", line 81, in _confirm_remove_internal
    if not icons.has_icon(icon_name):
TypeError: Gtk.IconTheme.has_icon() argument 1 must be string, not None