Remove duplicate existence check in enum classes

[codecov[bot]]

Codecov Report

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

Comparison is base (653216e) 99.88% compared to head (89e0708) 100.00%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #168 +/- ## ============================================= + Coverage 99.88% 100.00% +0.11% + Complexity 233 231 -2 ============================================= Files 33 33 Lines 3615 3611 -4 ============================================= Hits 3611 3611 + Misses 4 0 -4 ```

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