golang-error-handling
Idiomatic Golang error handling — creation, wrapping with %w, errors.Is/As, errors.Join, custom error types, sentinel errors, panic/recover, the single handling rule, structured logging with slog, HTTP request logging middleware, and samber/oops for production errors. Built to make logs usable at scale with log aggregation 3rd-party tools. Apply when creating, wrapping, inspecting, or logging errors in Go code. For samber/oops specifics → See samber/cc-skills-golang@golang-samber-oops skill; for slog handler ecosystem → See samber/cc-skills-golang@golang-samber-slog skill.
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Install
Works with every agent the skills CLI supports.
npx skills add https://github.com/samber/cc-skills-golang --skill golang-error-handling- 01
Install
Run the command in your project. The CLI asks which agents to install for.
- 02
Describe the task
Ask your agent for something this skill covers. It loads golang-error-handling automatically when relevant.
- 03
Review the result
The agent follows the SKILL.md steps, scripts and references bundled with the skill.
Security audits
Independent scans of the skill's instructions and bundled files.
SKILL.md
The instructions your agent reads when the skill is triggered.
Persona: You are a Go reliability engineer. You treat every error as an event that must either be handled or propagated with context — silent failures and duplicate logs are equally unacceptable.
Orchestration mode: Fan out the five category sub-agents described in the "Parallelizing Error Handling Audits" section (creation, wrapping, single-handling rule, panic/recover, structured logging) for auditing error handling across a large codebase, and consolidate their findings. On Claude Code, use ultracode to opt into multi-agent orchestration explicitly.
Modes:
- Coding mode — writing new error handling code. Follow the best practices sequentially; optionally launch a background sub-agent to grep for violations in adjacent code (swallowed errors, log-and-return pairs) without blocking the main implementation.
- Review mode — reviewing a PR's error handling changes. Focus on the diff: check for swallowed errors, missing wrapping context, log-and-return pairs, and panic misuse. Sequential.
- Audit mode — auditing existing error handling across a codebase. Use up to 5 parallel sub-agents, each targeting an independent category (creation, wrapping, single-handling rule, panic/recover, structured logging).
Community default. A company skill that explicitly supersedes
samber/cc-skills-golang@golang-error-handlingskill takes precedence.
Go Error Handling Best Practices
This skill guides the creation of robust, idiomatic error handling in Go applications. Follow these principles to write maintainable, debuggable, and production-ready error code.
Best Practices Summary
- Returned errors MUST always be checked — NEVER discard with
_ - Errors MUST be wrapped with context using
fmt.Errorf("{context}: %w", err) - Error strings MUST be lowercase, without trailing punctuation
- Use
%winternally,%vat system boundaries to control error chain exposure - MUST use
errors.Isfor sentinel matching anderrors.As/errors.AsTypefor typed chain inspection instead of direct comparison or bare type assertions. For Go 1.26+, prefererrors.AsType[T](err)whenTimplementserror; useerrors.As(err, &target)for Go <1.26 or for non-error interface targets. - SHOULD use
errors.Join(Go 1.20+) to combine independent errors - Errors MUST be either logged OR returned, NEVER both (single handling rule)
- Use sentinel errors for expected conditions, custom types for carrying data
- NEVER use
panicfor expected error conditions — reserve for truly unrecoverable states - SHOULD use
slog(Go 1.21+) for structured error logging — notfmt.Printlnorlog.Printf - Use
samber/oopsfor production errors needing stack traces, user/tenant context, or structured attributes - Log HTTP requests with structured middleware capturing method, path, status, and duration
- Use log levels to indicate error severity
- Never expose technical errors to users — translate internal errors to user-friendly messages, log technical details separately
- Keep log grouping low-cardinality — at logging/APM boundaries, keep message templates stable and attach IDs, paths, line numbers, and counts as structured attributes. Error values may include useful operational context, but avoid putting high-cardinality data into the stable log message used for grouping.
Detailed Reference
-
Error Creation — How to create errors that tell the story: error messages should be lowercase, no punctuation, and describe what happened without prescribing action. Covers sentinel errors (one-time preallocation for performance), custom error types (for carrying rich context), and the decision table for which to use when.
-
Error Wrapping and Inspection — Why
fmt.Errorf("{context}: %w", err)beatsfmt.Errorf("{context}: %v", err)(chains vs concatenation). How to inspect chains witherrors.Is,errors.As, and Go 1.26+errors.AsTypefor type-safe error handling, anderrors.Joinfor combining independent errors. -
Error Handling Patterns and Logging — The single handling rule: errors are either logged OR returned, NEVER both (prevents duplicate logs cluttering aggregators). Panic/recover design,
samber/oopsfor production errors, andslogstructured logging integration for APM tools.
Parallelizing Error Handling Audits
When auditing error handling across a large codebase, use up to 5 parallel sub-agents — each targets an independent error category:
- Sub-agent 1: Error creation — validate
errors.New/fmt.Errorfusage, low-cardinality messages, custom types - Sub-agent 2: Error wrapping — audit
%wvs%v, verifyerrors.Is/errors.Aspatterns - Sub-agent 3: Single handling rule — find log-and-return violations, swallowed errors, discarded errors (
_) - Sub-agent 4: Panic/recover — audit
panicusage, verify recovery at goroutine boundaries - Sub-agent 5: Structured logging — verify
slogusage at error sites, check for PII in error messages
Cross-References
- → See
samber/cc-skills-golang@golang-samber-oopsfor full samber/oops API, builder patterns, and logger integration - → See
samber/cc-skills-golang@golang-observabilityfor structured logging setup, log levels, and request logging middleware - → See
samber/cc-skills-golang@golang-safetyfor nil interface trap and nil error comparison pitfalls - → See
samber/cc-skills-golang@golang-namingfor error naming conventions (ErrNotFound, PathError) - → See
samber/cc-skills-golang@golang-continuous-integrationskill for automated AI-driven code review in CI using these guidelines
References
FAQ
What does the golang-error-handling skill do?
Idiomatic Golang error handling — creation, wrapping with %w, errors.Is/As, errors.Join, custom error types, sentinel errors, panic/recover, the single handling rule, structured logging with slog, HTTP request logging middleware, and samber/oops for production errors. Built to make logs usable at scale with log aggregation 3rd-party tools. Apply when creating, wrapping, inspecting, or logging errors in Go code. For samber/oops specifics → See samber/cc-skills-golang@golang-samber-oops skill; for slog handler ecosystem → See samber/cc-skills-golang@golang-samber-slog skill.
How do I install golang-error-handling?
Run npx skills add https://github.com/samber/cc-skills-golang --skill golang-error-handling in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/golang-error-handling/ (personal) or .claude/skills/golang-error-handling/ (project).
Which AI agents can use golang-error-handling?
Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.
Is golang-error-handling safe to install?
Security partners have reviewed it: Gen Agent Trust Hub passed; Socket passed; Snyk passed; ZeroLeaks passed. As with any skill, read the SKILL.md and bundled scripts before installing.
Who maintains golang-error-handling?
It is published by samber in samber/cc-skills-golang. It has 43,630 recorded installs.
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