Apply review suggestions for economic representation calculation

[gnawin]

Fixes #1095

Checklist before merging

• Documentation is up-to-date
• Unit tests have been added/updated accordingly
• Code has been formatted according to SpineOpt's style
• Unit tests pass

[codecov]

Codecov Report

Attention: Patch coverage is 97.67442% with 1 line in your changes missing coverage. Please review.

Project coverage is 87.30%. Comparing base (7bc3fcf) to head (b330d27).
Report is 30 commits behind head on master.

Files with missing lines	Patch %	Lines
src/data_structure/economic_structure.jl	97.67%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1130      +/-   ##
==========================================
- Coverage   87.33%   87.30%   -0.04%     
==========================================
  Files         143      143              
  Lines        4137     4134       -3     
==========================================
- Hits         3613     3609       -4     
- Misses        524      525       +1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

---

🚨 Try these New Features:

• Flaky Tests Detection - Detect and resolve failed and flaky tests