feat(errors): expose isOwnInstance to createCustomError's constructCb and skip redundant stack captures

[nev21]

Custom errors built with createCustomError can extend other custom errors, chaining constructCb calls at every level. There was previously no way for a level to know whether it was the leaf class actually being instantiated or just running as a base-class step for some subclass further down the chain, so hierarchies with their own per-level stack capture logic (e.g. a TripwireError -> AssertionError -> AssertionFailure -> AssertionFatal chain) had no way to skip that work except at the leaf.

• constructCb now receives a 3rd argument, isOwnInstance, computed by comparing the instance's resolved constructor against the class's own constructor function via a self-referencing named function expression The internal automatic Error.captureStackTrace call is now gated by the same isOwnInstance check, so it only fires once per instance (at the leaf-most class) instead of redundantly at every level of a chain
• Add regression tests covering the internal capture optimization and isOwnInstance correctness across single classes, multi-level chains, and a class used both directly and as a base

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.17%. Comparing base (4d61687) to head (d016feb).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #587   +/-   ##
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  Coverage   99.17%   99.17%           
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  Files         179      179           
  Lines        5475     5479    +4     
  Branches     1209     1210    +1     
=======================================
+ Hits         5430     5434    +4     
  Misses         45       45           

Files with missing lines	Coverage Δ
lib/src/helpers/customError.ts	100.00% <100.00%> (ø)

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[Copilot]

Pull request overview

This PR improves createCustomError to better support multi-level custom error inheritance by exposing whether a constructor is running for the leaf-most instance and by avoiding redundant internal Error.captureStackTrace calls across a base-class chain.

Changes:

• Extend createCustomError’s constructCb callback to receive a 3rd isOwnInstance argument indicating leaf-most instantiation.
• Gate the internal automatic Error.captureStackTrace call so it only runs once per instance (at the leaf-most class).
• Add regression tests validating single-capture behavior and isOwnInstance semantics across inheritance chains.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

File	Description
lib/src/helpers/customError.ts	Adds isOwnInstance detection and gates internal stack capture to avoid repeated work in inheritance chains.
lib/test/src/common/helpers/throw.test.ts	Adds regression tests for single stack capture and isOwnInstance behavior across direct and chained instantiation.

[nevware21-bot]

Approved by nevware21-bot