Description of problem:
In blivet-GUI in Anaconda I clicked on button with bulb icon to show details of partition. Dialog window popped up, but did not react on any input and after while dialog about bug was shown.

Version-Release number of selected component:
anaconda-29.24.3

The following was filed automatically by anaconda:
anaconda 29.24.3 exception report
Traceback (most recent call first):
  File "/usr/lib/python3.7/site-packages/blivetgui/dialogs/size_chooser.py", line 777, in default_unit
    return self.available_units[-1]
  File "/usr/lib/python3.7/site-packages/blivetgui/dialogs/size_chooser.py", line 693, in __init__
    self.selected_unit = self.default_unit
  File "/usr/lib/python3.7/site-packages/blivetgui/dialogs/size_chooser.py", line 105, in __init__
    self.main_chooser = SizeChooser(max_size=self.max_size, min_size=self.min_size)
  File "/usr/lib/python3.7/site-packages/blivetgui/dialogs/add_dialog.py", line 699, in add_size_area
    raid_type=raid_level)
  File "/usr/lib/python3.7/site-packages/blivetgui/dialogs/add_dialog.py", line 929, in on_devices_combo_changed
    self.add_size_area()
IndexError: list index out of range

Additional info:
addons:         com_redhat_docker, com_redhat_kdump
blivet-gui-utils.log: 
cmdline:        /usr/bin/python3  /sbin/anaconda
cmdline_file:   initrd=/distrotrees/95173/initrd method=http://download.eng.brq.redhat.com/pub/fedora/fedmsg/dumpdata/Fedora-29-20180929.n.0/Workstation/x86_64/os/ repo=http://download.eng.brq.redhat.com/pub/fedora/fedmsg/dumpdata/Fedora-29-20180929.n.0/Workstation/x86_64/os/  BOOT_IMAGE=/distrotrees/95173/kernel 
executable:     /sbin/anaconda
hashmarkername: anaconda
kernel:         4.18.9-300.fc29.x86_64
product:        Fedora
release:        Cannot get release name.
release_type:   pre-release
type:           anaconda
version:        29