Mask inside logged errors instead of passing them through

[nkuba]

Masking does not reach inside errors. With mask: { regex: [/SECRET_[0-9]+/] }:

log.info("key=SECRET_123");             // key=[***]
log.error(new Error("key=SECRET_123")); // key=SECRET_123

The error message, properties assigned to the error and the whole cause chain reach the JSON line, the pretty output and every transport in plaintext. Reported in #361, and for assigned properties in #214.

This PR makes the masking engine treat an Error like any other argument: it is replaced by a masked clone. The clone is a real Error with the same prototype, so instanceof and the JSON error detection still work, and no subclass constructor runs. The original error is not modified.

What gets masked inside an error:

• mask.regex: the message, and the <name>: <message> header line of a V8 stack. Stack frames are left alone, so a broad pattern cannot break file positions.
• mask.keys and mask.paths: every other own property (code, extensions, ...) and the cause chain. keys skips name, message and stack, so keys: ["name"] does not blank every error.

One behavior change for transports: with mask configured, nativeError is now the masked clone, not the caller's instance. Without mask nothing changes. The changelog entry sits under 5.2.0 for that reason.

Fixes #361

[terehov]

Thank you. I’ll have a look at it in a few days 🙏

[terehov]

Thanks for this, the fix is solid and well tested.

I added one commit on top: DOMException (e.g. AbortError from fetch/AbortController) serves name and message through prototype getters that read internal slots, so they threw on the prototype-swapped clone and the error was logged as Error: with an empty message. The clone now copies those two from the source when its getter can't answer them (Node + browser test). I also added the masked-clone note to RECIPES.md.

[codecov]

Codecov Report

❌ Patch coverage is 97.01493% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 99.83%. Comparing base (c857dd4) to head (f2b01ec).
⚠️ Report is 24 commits behind head on development.

Files with missing lines	Patch %	Lines
src/core/masking.ts	97.02%	2 Missing ⚠️

Additional details and impacted files

@@               Coverage Diff               @@
##           development     #362      +/-   ##
===============================================
- Coverage       100.00%   99.83%   -0.17%     
===============================================
  Files               54       53       -1     
  Lines             7256     4643    -2613     
  Branches          2228     1369     -859     
===============================================
- Hits              7256     4635    -2621     
- Misses               0        8       +8     

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