style: minor adjustments

[georglauterbach]

Description

These adjustments are just follow-ups for the latest PRs I merged. If you have more adjustments, feel free to add them to this PR.

Type of change

• [x] Improvement (non-breaking change that does improve existing functionality)

Checklist:

• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my own code
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] I have made corresponding changes to the documentation (README.md or the documentation under docs/)
• [x] If necessary I have added tests that prove my fix is effective or that my feature works
• [x] New and existing unit tests pass locally with my changes