go/error-handling

Wrap errors in Go by using fmt.Errorf with the %w verb to propagate operation context. This preserves the original error chain, allowing callers to inspect underlying causes while adding diagnostic information across package boundaries.

Aggregate multiple errors in Go using errors.Join. This function collects multiple error values into a single error, enabling multi-error aggregation for batch operations or validation checks where multiple failures need to be reported together.

errors.Is checks if an error matches a specific sentinel value within a wrapped chain, while errors.As extracts structured details from custom error types. Use errors.As to unpack custom error fields for HTTP error mapping and diagnostics.

Map Go domain errors to HTTP responses by inspecting error chains with errors.Is and errors.As at API boundaries. Translate sentinel errors and custom error types into appropriate HTTP status codes, ensuring consistent error rendering for clients.

Use sentinel errors for predefined common conditions like "not found" or "unauthorized" that require simple equality checks. Use custom error types when you need to carry structured diagnostic data that callers must extract using errors.As.