Description of problem:
1. Opened firewall-config
2. Error message popped up.
3. Acknowledging message (OK) did not remove it. Cancel closed firewall-config.
4. Attempts to repeat result in goto 1.

Version-Release number of selected component:
firewall-config-0.3.13-2.fc21

Additional info:
reporter:       libreport-2.3.0
cmdline:        /usr/bin/python -Es /bin/firewall-config
executable:     /bin/firewall-config
kernel:         3.18.7-200.fc21.x86_64
runlevel:       N 5
type:           Python
uid:            0

Truncated backtrace:
firewall-config:2024:onChangeZone:TypeError: 'NoneType' object has no attribute '__getitem__'

Traceback (most recent call last):
  File "/bin/firewall-config", line 2024, in onChangeZone
    _services = services[:]
TypeError: 'NoneType' object has no attribute '__getitem__'

Local variables in innermost frame:
masquerade: None
default: False
interfaces: None
args: (<TreeSelection object at 0x7f67cc1bbbe0 (GtkTreeSelection at 0x2069920)>,)
self: <__main__.FirewallConfig object at 0x7f67cc22e950>
sources: None
builtin: False
icmpblocks: None
rules: None
services: None
selected_zone: 'home'
ports: None
forward_ports: None