Fix suggestions from CodeQL scan

[giffels]

This pull request addresses all warnings from CodeQL scan. It fixes #268, fixes #269, fixes #270, fixes #271

• [x] #268
• [x] #269
• [x] #270
• [x] #271

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (0348c67) 98.86% compared to head (880c5e0) 98.87%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #317 +/- ## ======================================= Coverage 98.86% 98.87% ======================================= Files 55 55 Lines 2210 2218 +8 ======================================= + Hits 2185 2193 +8 Misses 25 25 ```

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