Description of problem:
I created an LVM LV using xfs, then deleted it, then applied the operations.

Version-Release number of selected component:
blivet-gui-2.0.2-1.fc25

Additional info:
reporter:       libreport-2.8.0
cmdline:        /usr/bin/python3 /usr/bin/blivet-gui
executable:     /usr/bin/blivet-gui
kernel:         4.10.12-200.fc25.x86_64
pkg_fingerprint: 4089 D8F2 FDB1 9C98
pkg_vendor:     Fedora Project
runlevel:       N 5
type:           Python3
uid:            1000

Truncated backtrace:
Gtk.py:1164:__new__:TypeError: could not parse subscript '-1' as a tree path

Traceback (most recent call last):
  File "/usr/lib64/python3.5/site-packages/gi/overrides/Gtk.py", line 1162, in __new__
    return TreePath.new_from_string(path)
TypeError: constructor returned NULL

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3.5/site-packages/blivetgui/blivetgui.py", line 477, in end
    dialog.stop()
  File "/usr/lib/python3.5/site-packages/blivetgui/processing_window.py", line 154, in stop
    self._set_applied_icon(self.finished_actions - 1)
  File "/usr/lib/python3.5/site-packages/blivetgui/processing_window.py", line 135, in _set_applied_icon
    path = Gtk.TreePath(position)
  File "/usr/lib64/python3.5/site-packages/gi/overrides/Gtk.py", line 1164, in __new__
    raise TypeError("could not parse subscript '%s' as a tree path" % path)
TypeError: could not parse subscript '-1' as a tree path

Local variables in innermost frame:
path: '-1'
cls: <class 'gi.overrides.Gtk.TreePath'>