Fix semconv generated error type to check error chain for custom type declaration

[MrAlias]

Fix ErrorType detection to work through wrapped error chains.

errorType previously only checked whether the top-level error value implemented ErrorType() string. In common Go usage, errors are often wrapped, so this could miss ErrorType implementations behind wrappers.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 81.6%. Comparing base (b2b3250) to head (d3b3479).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
semconv/v1.40.0/error_type.go	0.0%	4 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #7994     +/-   ##
=======================================
- Coverage   81.6%   81.6%   -0.1%     
=======================================
  Files        304     304             
  Lines      23385   23389      +4     
=======================================
- Hits       19091   19090      -1     
- Misses      3905    3911      +6     
+ Partials     389     388      -1     

Files with missing lines	Coverage Δ
semconv/v1.40.0/error_type.go	0.0% <0.0%> (ø)

... and 3 files with indirect coverage changes

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[Copilot]

Pull request overview

This PR updates the semconv ErrorType helper to detect custom ErrorType() string implementations through wrapped error chains (using errors.As), aligning behavior with common Go error-wrapping patterns.

Changes:

• Update errorType to use errors.As so wrapped errors can contribute ErrorType() string.
• Update doc comments to describe chain-aware ErrorType detection.
• Extend generated tests (and templates) to cover wrapped errors.

Reviewed changes

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

File	Description
semconv/v1.40.0/error_type.go	Switches ErrorType detection from direct assertion to chain-aware errors.As; updates docs accordingly.
semconv/v1.40.0/error_type_test.go	Adds coverage for wrapped errors and empty ErrorType values in the chain.
internal/tools/semconvkit/templates/error_type.go.tmpl	Updates generator template to emit the new chain-aware implementation and docs.
internal/tools/semconvkit/templates/error_type_test.go.tmpl	Updates generator template tests to validate wrapped-error behavior.

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[pellared]

Fixes #7975 ?

Shouldn't we unwrap even if it does not implement ErrorType() method?

[MrAlias]

Fixes #7975 ?

Shouldn't we unwrap even if it does not implement ErrorType() method?

I think that is a different discussion. I don't see it in the scope of this PR. This is addressing the linked feedback from the previous PR review addressing specifically the detection of the ErrorType() string interface.

[seh]

I agree with @MrAlias that this patch does not fix #7975, even though it addresses a similar blindness with a similar remediation. The word isomorphic comes to mind.