fix: bugs related to `observed`

[AayushSabharwal]

Checklist

• [ ] Appropriate tests were added
• [ ] Any code changes were done in a way that does not break public API
• [ ] All documentation related to code changes were updated
• [ ] The new code follows the contributor guidelines, in particular the SciML Style Guide and COLPRAC.
• [ ] Any new documentation only uses public API

Additional context

Add any other context about the problem here.

[codecov[bot]]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (0c62711) 26.25% compared to head (2a887de) 38.83%. Report is 18 commits behind head on master.

Files	Patch %	Lines
src/scimlfunctions.jl	80.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #615 +/- ## =========================================== + Coverage 26.25% 38.83% +12.57% =========================================== Files 54 55 +1 Lines 4113 4259 +146 =========================================== + Hits 1080 1654 +574 + Misses 3033 2605 -428 ```

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