op_mode: T6808: Console server op mode commands throw errors when console server is not configured

[natali-rs1985]

Change Summary

Types of changes

• [x] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Code style update (formatting, renaming)
• [ ] Refactoring (no functional changes)
• [ ] Migration from an old Vyatta component to vyos-1x, please link to related PR inside obsoleted component
• [ ] Other (please describe):

Related Task(s)

• https://vyos.dev/T6808

Related PR(s)

Component(s) name

op-mode

Proposed changes

How to test

Op-mode command show console-server ports without configured console-server (before):

vyos@vyos:~$ show console-server ports
console: Unable to connect to 127.0.0.1:3109

After fix:

vyos@vyos:~$ show console-server ports
Console server is not configured

Smoketest result

Checklist:

• [x] I have read the CONTRIBUTING document
• [x] I have linked this PR to one or more Phabricator Task(s)
• [ ] I have run the components SMOKETESTS if applicable
• [x] My commit headlines contain a valid Task id
• [ ] My change requires a change to the documentation
• [ ] I have updated the documentation accordingly