/golang-error-handling

Standards for error wrapping, checking, and definition in Golang. Use when wrapping errors, defining sentinel errors, or handling errors idiomatically in Go.

hoangnguyen0403@hoangnguyen0403

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Standards for error wrapping, checking, and definition in Golang. Use when wrapping errors, defining sentinel errors, or handling errors idiomatically in Go.

SKILL.md

golang-error-handling.SKILL.md

name: golang-error-handling
description: Standards for error wrapping, checking, and definition in Golang. Use when wrapping errors, defining sentinel errors, or handling errors idiomatically in Go.
metadata:
  triggers:
    files:
    - 'fmt.Errorf'
    - 'errors.Is'
    - 'errors.As'
    keywords:
    - error wrapping
    - sentinel error
    - error handling

Golang Error Handling Standards

Priority: P0 (CRITICAL)

Principles

**Errors Values**: Handle them like any other value.
**Handle Once**: Log OR Return. Never Log AND Return (creates duplicate logs).
**Add Context**: Don't return `err` bubble up. Wrap it with context: `fmt.Errorf("failed to open file: %w", err)`.
**Use Standard Lib**: Go 1.13+ `errors` package (`Is`, `As`, `Unwrap`) sufficient. Avoid `pkg/errors` (deprecated).

Guidelines

**Sentinel Errors**: Expoted, fixed errors (`io.EOF`, `sql.ErrNoRows`). Use `errors.Is(err, io.EOF)`.
**Error Types**: Structs implementing `error`. Use `errors.As(err, &target)`.
**Panic**: Only for unrecoverable startup errors.

Anti-Patterns

**No bare return err**: Wrap with `fmt.Errorf("context: %w", err)` to preserve call chain.
**No string error checks**: Use `errors.Is`/`errors.As`; string comparison brittle.
**No swallowed errors**: Never assign errors to `_`; always handle or propagate.