fix: duplicate error output

[lechnerc77]

Purpose

• Fix duplicate error output when entering wrong flags or commands

Does this introduce a breaking change?

[ ] Yes
[X] No

Pull Request Type

What kind of change does this Pull Request introduce?

[X] Bugfix
[ ] Feature
[ ] Refactoring (no functional changes, no api changes)
[ ] Documentation content changes
[ ] Other... Please describe:

How to Test

• Test the code via automated test

make test

• Additional test steps

Enter a wrong command or use wrong flags in the CLI

What to Check

Verify that the following are valid:

• Automated tests are executed successfully
• The error message of unsupported flags/commands is shown once only

Other Information

n/a

Checklist for reviewer

The following organizational tasks must be completed before merging this PR:

• [X] The PR is assigned to the Project board and a status is set (typically "in review").
• [X] The PR has the matching labels assigned to it.
• [X] The PR has a milestone assigned to it.
• [X] If the PR closes an issue, the issue is referenced.
• [X] Possible follow-up issues are created and linked.