fix: fix getu with parameter symbols

[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]

Codecov Report

Attention: Patch coverage is 0% with 7 lines in your changes are missing coverage. Please review.

Project coverage is 38.17%. Comparing base (a7c70c8) to head (ad18dbf).

Files	Patch %	Lines
src/state_indexing.jl	0.00%	7 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #55      +/-   ##
==========================================
- Coverage   38.83%   38.17%   -0.66%     
==========================================
  Files           7        7              
  Lines         291      296       +5     
==========================================
  Hits          113      113              
- Misses        178      183       +5     

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