worker: fix messageerror listener cleanup

[kiliczsh]

Worker exit cleanup attempts to remove messageerror listeners before
emitting the exit event, but uses the non-existent messageerrors event
name. As a result, messageerror listeners are still present while exit
listeners run, unlike message listeners.

Use the correct event name during cleanup. Add a regression test covering
both normal worker exit and termination with worker.terminate().

Fixes: #65782

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.06%. Comparing base (7551e1d) to head (c21a0a2).
⚠️ Report is 16 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #65783   +/-   ##
=======================================
  Coverage   90.05%   90.06%           
=======================================
  Files         769      769           
  Lines      261396   261396           
  Branches    49631    49620   -11     
=======================================
+ Hits       235399   235414   +15     
+ Misses      17034    17020   -14     
+ Partials     8963     8962    -1     

Files with missing lines	Coverage Δ
lib/internal/worker.js	97.02% <100.00%> (ø)

... and 26 files with indirect coverage changes

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[MikeMcC399]

The recommendations in:

• Guides and FAQs for first-time contributors

advise you should tackle only one issue at a time and that you should not open any new PRs until your first PR has been approved.

You already have #65776 open and this has not yet been reviewed or approved.

[kiliczsh]

Thanks for heads up @MikeMcC399. I will close this PR and watch #65776.