Return clear error messages when outputPath or parameterPath are invalid

[rengelke]

Closes #709

[codecov[bot]]

Codecov Report

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

Project coverage is 88.40%. Comparing base (b6487c2) to head (07a4d41). Report is 2 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #712 +/- ## ========================================== + Coverage 88.35% 88.40% +0.05% ========================================== Files 29 29 Lines 2730 2742 +12 ========================================== + Hits 2412 2424 +12 Misses 318 318 ```

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