refactor(pattern-router): reduce bundle size and fix comments

[EdamAme-x]

I noticed that there is no need to declare using let.
Also, one comment was incorrect and has been corrected.

The author should do the following, if applicable

• Add tests
• Run tests
• bun run format:fix && bun run lint:fix to format the code
• Add TSDoc/JSDoc to document the code

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.29%. Comparing base (c9bd830) to head (d0b5508).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3936      +/-   ##
==========================================
- Coverage   91.32%   91.29%   -0.04%     
==========================================
  Files         168      168              
  Lines       10686    10772      +86     
  Branches     3061     3173     +112     
==========================================
+ Hits         9759     9834      +75     
- Misses        926      937      +11     
  Partials        1        1              

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[yusukebe]

LGTM!

[yusukebe]

@EdamAme-x Thank you!