fix: use safe property checks

[pi0]

🔗 Linked issue

Ref unjs/nitro#1637

❓ Type of change

• 📖 Documentation (updates to the documentation, readme, or JSdoc annotations)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality like performance)
• ✨ New feature (a non-breaking change that adds functionality)
• 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

in operator expects the right hand to be an Object and can easily lead to edge case issues when we check something like 'foo' in 2 > Uncaught TypeError: Cannot use 'in' operator to search for 'foo' in 2.

This PR uses a small shared util for safer checks.

📝 Checklist

• I have linked an issue or discussion.
• I have updated the documentation accordingly.

[codecov]

Codecov Report

Merging #521 (27082e4) into main (164f68e) will increase coverage by 0.03%.
The diff coverage is 90.32%.

@@            Coverage Diff             @@
##             main     #521      +/-   ##
==========================================
+ Coverage   82.11%   82.15%   +0.03%     
==========================================
  Files          31       32       +1     
  Lines        3646     3665      +19     
  Branches      536      543       +7     
==========================================
+ Hits         2994     3011      +17     
- Misses        652      654       +2     

Files Changed	Coverage Δ
src/event/event.ts	86.71% <50.00%> (+0.10%)	⬆️
src/utils/internal/object.ts	75.00% <75.00%> (ø)
src/error.ts	80.55% <100.00%> (+0.10%)	⬆️
src/event/utils.ts	58.62% <100.00%> (+0.23%)	⬆️
src/utils/body.ts	94.57% <100.00%> (+0.02%)	⬆️
src/utils/response.ts	78.67% <100.00%> (+0.42%)	⬆️