Protocol IS-IS configuration is empty
To reproduce:
```
set interfaces dummy dum0 address '203.0.113.254/32'
set interfaces dummy dum0 description 'dum0'
set interfaces ethernet eth1 address '192.0.2.5/24'
set interfaces ethernet eth1 description 'LAN'
set interfaces tunnel tun0 address '10.0.0.2/30'
set interfaces tunnel tun0 description 'tun-to-192.0.2.1'
set interfaces tunnel tun0 encapsulation 'gre'
set interfaces tunnel tun0 source-address '192.0.2.5'
set protocols isis interface eth1
set protocols isis interface tun0
set protocols isis lsp-mtu '1460'
set protocols isis net '49.0001.1920.0200.0011.00'
set protocols isis redistribute ipv4 connected level-2
```
Check:
```
vyos@r1# vtysh -c "show run isisd"
Building configuration...
Current configuration:
!
hostname r1
service integrated-vtysh-config
!
end
[edit]
vyos@r1#
```
The thing is, there is no ip `remote` address for the tunnel `tun0`
If we add the remote address and re-configure `protocol isis`, the configuration looks good again
```
set interfaces tunnel tun0 remote '192.0.2.1'
```