Join errors so they are detectable by errors.Is

[casey-tran]

Description:

The purpose of this PR is to have both of the errors emitted by their log lines be joined so that they are detectable by isFatal in `handlers.go.

Checklist:

• Tests passing (make test-community)?
• Lint passing (make lint this requires golangci-lint)?

---

Note

Low Risk
Small change limited to error composition in non-archive chunk processing; main risk is altered error strings/unwrap structure affecting tests or log expectations.

Overview
Updates defaultHandler.handleNonArchiveContent error wrapping to use errors.Join so emitted chunk read/write errors retain ErrProcessingWarning/ErrProcessingFatal in the error chain and can be detected via errors.Is (e.g., by isFatal).

This changes the formatting of the propagated errors to wrap the joined sentinel+underlying error as the %w cause while keeping the log message text stable ("error reading chunk" / "error writing to data channel").

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[casey-tran]

A concern is that the error error reading chunk can be caused by a context deadline being exceeded, which we want to treat as a fatal error in isFatal but since the intention of ErrProcessingWarning is to have an error that is able to move on, we seem to have a divergence of intent.

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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[cursor]

Joined warning errors may be misclassified as fatal

Medium Severity

Using errors.Join(ErrProcessingWarning, err) preserves the full error chain of the inner err. If that error wraps context.Canceled or context.DeadlineExceeded (possible when the underlying reader is a network stream or pipe), isFatal will match the first switch case (fatal) before reaching the ErrProcessingWarning case (non-fatal). This causes a supposedly recoverable warning to terminate file processing, contradicting the explicit continue on the next line. The old %v formatting intentionally broke the inner error chain to prevent this.

 

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