test: cover Readable.from() sync iterator errors

[jakecastelli]

Adds regression coverage for Readable.from() when consuming synchronous iterators across null-value and promise-rejection paths which we don't have coverage atm.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.15%. Comparing base (82babee) to head (e1ce5bd).
⚠️ Report is 36 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #65515      +/-   ##
==========================================
+ Coverage   90.12%   90.15%   +0.02%     
==========================================
  Files         751      751              
  Lines      252543   253550    +1007     
  Branches    47516    47769     +253     
==========================================
+ Hits       227611   228583     +972     
+ Misses      16244    16197      -47     
- Partials     8688     8770      +82     

see 67 files with indirect coverage changes

🚀 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.