Fix CSV logger warning

[carmocca]

What does this PR do?

Fixes warning appearing with an empty log_dir

Before submitting

• Was this discussed/approved via a Github issue? (no need for typos and docs improvements)
• Did you read the contributor guideline, Pull Request section?
• Did you make sure your PR does only one thing, instead of bundling different changes together? Otherwise, we ask you to create a separate PR for every change.
• [n/a] Did you make sure to update the documentation with your changes?
• [n/a] Did you write any new necessary tests?
• Did you verify new and existing tests pass locally with your changes?
• [n/a] If you made a notable change (that affects users), did you update the CHANGELOG?

PR review

• Is this pull request ready for review? (if not, please submit in draft mode)

[codecov]

Codecov Report

Merging #4419 into master will decrease coverage by 0%.
The diff coverage is 100%.

@@          Coverage Diff           @@
##           master   #4419   +/-   ##
======================================
- Coverage      93%     93%   -0%     
======================================
  Files         111     111           
  Lines        8064    8064           
======================================
- Hits         7485    7474   -11     
- Misses        579     590   +11