Fix nil-pointer panic when GitHub returns a rate-limit error

[alyssajoyner]

What

sanitizeGitHubError now flattens all go-github error types with a custom Is method (ErrorResponse, RateLimitError, AbuseRateLimitError, AcceptedError, RedirectionError) to a plain error, not just ErrorResponse.

Why

When GitHub rate-limits a query, go-github returns a *RateLimitError, whose Is method calls errors.As(target, &v). The SDK's guessErrorStatus classifies errors via errors.Is(err, (*url.Error)(nil)) (a typed-nil target), which routes into RateLimitError.Is and calls (*url.Error).Unwrap on a nil receiver, panicking. The panic is recovered as a plugin.requestFailureError, so it counts against the DatasourcePluginQuerySuccessRate SLO.

sanitizeGitHubError already guarded against this but only for ErrorResponse; all five types share the same unsafe Is. Flattening with fmt.Errorf("%s", ...) (not %w) drops the Is method while keeping the message, so downstream classification is unaffected.

[cla-assistant]

All committers have signed the CLA.

[Copilot]

Pull request overview

This pull request prevents a nil-pointer panic during datasource error-source classification by guarding access to go-github’s embedded *http.Response before reading StatusCode. This keeps request failures from being misclassified via an SDK panic path and aligns the classification behavior with the intended error handling flow.

Changes:

• Add a defensive check for resp.Response != nil before reading resp.StatusCode in addErrorSourceToError.
• Add a regression test covering the “non-nil wrapper Response with nil inner *http.Response” scenario.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
pkg/github/client/errorsourcehandling.go	Avoids nil-pointer panic by guarding the embedded *http.Response before using StatusCode.
pkg/github/client/errorsourcehandling_test.go	Adds a test to ensure the nil inner *http.Response case does not panic and preserves the error.

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