test: guard balanced-pool error port lookup

[mcollina]

This relates to...

Windows flake in test/node-test/balanced-pool.js where an error object may not include nested socket metadata.

Rationale

The weighted round-robin test assumed all request errors expose error.socket.remotePort. On Windows, some transient errors can be missing socket, causing the test harness to throw a masking TypeError instead of handling or surfacing the original error.

Changes

Features

N/A

Bug Fixes

• Add a helper to safely read ports from request errors.
• Handle AggregateError children with the same safe lookup.
• Rethrow the original error when it cannot be mapped to a test server.

Breaking Changes and Deprecations

N/A

Status

• I have read and agreed to the Developer's Certificate of Origin
• Tested
• Benchmarked (optional)
• Documented
• Review ready
• In review
• Merge ready

Tested with:

• npx borp -p "test/node-test/balanced-pool.js"
• npm run lint -- test/node-test/balanced-pool.js
• git diff --check

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.47%. Comparing base (667d8a3) to head (68eeca8).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5463      +/-   ##
==========================================
- Coverage   93.48%   93.47%   -0.02%     
==========================================
  Files         110      110              
  Lines       37115    37115              
==========================================
- Hits        34697    34693       -4     
- Misses       2418     2422       +4     

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

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.