Cleanup classical simulator code and fix a couple of bugs

[codecov[bot]]

Codecov Report

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

Comparison is base (b5b3b74) 97.84% compared to head (83ef04d) 97.84%. Report is 4 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #6344 +/- ## ======================================= Coverage 97.84% 97.84% ======================================= Files 1110 1110 Lines 96690 96710 +20 ======================================= + Hits 94606 94626 +20 Misses 2084 2084 ```

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