Reported via Forums: https://forum.vyos.io/t/error-committing-dhcp-server-configuration-nameerror/6408
Reproducible via:
```
set service dhcp-server shared-network-name LAN authoritative
set service dhcp-server shared-network-name LAN subnet 192.168.2.0/24 default-router 192.168.2.1
set service dhcp-server shared-network-name LAN subnet 192.168.2.0/24 dns-server 192.168.2.1
set service dhcp-server shared-network-name LAN subnet 192.168.2.0/24 domain-name vyos.net
set service dhcp-server shared-network-name LAN subnet 192.168.2.0/24 exclude 192.168.2.1
set service dhcp-server shared-network-name LAN subnet 192.168.2.0/24 lease 192.168.2.1
set service dhcp-server shared-network-name LAN subnet 192.168.2.0/24 lease 86400
set service dhcp-server shared-network-name LAN subnet 192.168.2.0/24 range 0 start 192.168.2.10
set service dhcp-server shared-network-name LAN subnet 192.168.2.0/24 range 0 stop 192.168.2.200
```
```
Traceback (most recent call last):
File "/usr/libexec/vyos/conf_mode/dhcp_server.py", line 291, in <module>
c = get_config()
File "/usr/libexec/vyos/conf_mode/dhcp_server.py", line 125, in get_config
for slice in dhcp_slice_range(subnet_config['exclude'], r_config):
File "/usr/libexec/vyos/conf_mode/dhcp_server.py", line 95, in dhcp_slice_range
if ra not in output:
NameError: name 'ra' is not defined
```