fix(context): don't throw the error with c.header() when it's finalized

[yusukebe]

Fixes #4055

This is based on #4055 (comment) by @usualoma. It is a "slightly overhead but simple" pattern. I think it's rare that it should catch the error with try/catch, so this simple implementation is better.

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

[github-actions]

Bundle size check

	main (b68da39)	#4078 (a694dd4)	+/-
Bundle Size (B)	18,976B	18,904B	-72B
Bundle Size (KB)	18.53K	18.46K	-0.07K

Compiler Diagnostics

	main (b68da39)	#4078 (a694dd4)	+/-
Files	261	261	0
Lines	116,443	116,434	-9
Identifiers	114,436	114,428	-8
Symbols	303,844	303,852	8
Types	214,831	214,828	-3
Instantiations	3,091,594	3,091,594	0
Memory used	444,601K	453,098K	8,497K
I/O read	0.02s	0.03s	0.01s
I/O write	0s	0s	0s
Parse time	0.66s	0.79s	0.13s
Bind time	0.28s	0.33s	0.05s
Check time	5.51s	5.66s	0.15s
Emit time	0s	0s	0s
Total time	6.45s	6.78s	0.33s

---

Reported by octocov

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.33%. Comparing base (b68da39) to head (6745a6a).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4078      +/-   ##
==========================================
+ Coverage   91.29%   91.33%   +0.03%     
==========================================
  Files         168      168              
  Lines       10774    10682      -92     
  Branches     3053     3143      +90     
==========================================
- Hits         9836     9756      -80     
+ Misses        937      925      -12     
  Partials        1        1              

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[yusukebe]

Hey @usualoma

I've made a PR based on your comment. I think "Slightly overhead but simple" is good. Can you review this?

[usualoma]

Hi @yusukebe. Thank you. LGTM!

[yusukebe]

@usualoma

Thanks! Merging.