🎨 Misc. code quality improvements

[burgholzer]

Description

This PR brings in a couple code quality improvements discovered when working on #538.

Checklist:

• The pull request only contains commits that are related to it.
• I have added appropriate tests and documentation.
• I have made sure that all CI jobs on GitHub pass.
• The pull request introduces no new warnings and follows the project's style guidelines.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (f3e105e) 91.2% compared to head (ade870e) 91.2%.

Additional details and impacted files

@@           Coverage Diff           @@
##            main    #547     +/-   ##
=======================================
- Coverage   91.2%   91.2%   -0.1%     
=======================================
  Files        130     130             
  Lines      13639   13639             
  Branches    2143    2144      +1     
=======================================
- Hits       12444   12442      -2     
- Misses      1195    1197      +2     

Flag	Coverage Δ
cpp	90.9% <100.0%> (-0.1%)	⬇️
python	99.5% <ø> (ø)

Files	Coverage Δ
src/parsers/qasm3_parser/passes/ConstEvalPass.cpp	84.3% <100.0%> (ø)

... and 1 file with indirect coverage changes