name	go-errors
description	Idiomatic Go error handling. This skill should be used when the user writes, reviews, or debugs Go error code — wrapping with `%w`, inspecting via `errors.Is`/`errors.As`, sentinel vs typed errors, `errors.Join`, or chasing a silently-swallowed or context-losing error. Pair with the `errorlint` linter (set it up via `go-linting`). Not for panics-as-control-flow or non-Go languages.

go-errors — Go error handling

Deterministic backstop: golangci-lint run --enable-only=errorlint, plus errcheck (in the standard set) for unchecked errors. Run the tool first; this skill is the judgment around it.

Rules

Wrap with %w when the caller may need to inspect the cause (Go 1.13): return fmt.Errorf("read config %s: %w", path, err). Use %v only to deliberately sever the chain (e.g. to avoid leaking an internal error type across an API boundary) — and say so.
The %v-where-%w trap: formatting a cause with %v discards the chain, so downstream errors.Is/errors.As silently fail. errorlint flags it.
Inspect with errors.Is (sentinel) / errors.As (typed) — never err == ErrX or a type assertion once any layer wraps, or you get sentinel breakage (the comparison silently stops matching). (Go 1.13; errors.As target must be a pointer.)
Sentinel errors (var ErrNotFound = errors.New("not found")) for expected, comparable conditions that are part of your API contract — keep the set small and documented. Typed errors (a struct implementing error) when callers need fields (*PathError).
errors.Join(err1, err2) (Go 1.20) to aggregate independent failures (cleanup, validation) — replaces manual concatenation and most third-party multierror use.
Never swallow: no _ = f() on an error you care about; no empty if err != nil {}. Handle, wrap-and-return, or (deliberately, with a comment) ignore.
Add context at each layer, log once at the boundary. Wrapping at every level and logging at every level produces duplicate noise — return wrapped, log at the top.
Error strings: lowercase, no trailing punctuation (they get wrapped): "cannot parse %q".

Sources

Go 1.13 errors — https://go.dev/blog/go1.13-errors
Code Review Comments (Error Strings, Handle Errors) — https://go.dev/wiki/CodeReviewComments
Uber Go Style Guide (Errors) — https://github.com/uber-go/guide

go-errors — Go error handling

Deterministic backstop: golangci-lint run --enable-only=errorlint, plus errcheck (in the standard set) for unchecked errors. Run the tool first; this skill is the judgment around it.

Rules

Wrap with %w when the caller may need to inspect the cause (Go 1.13): return fmt.Errorf("read config %s: %w", path, err). Use %v only to deliberately sever the chain (e.g. to avoid leaking an internal error type across an API boundary) — and say so.

The %v-where-%w trap: formatting a cause with %v discards the chain, so downstream errors.Is/errors.As silently fail. errorlint flags it.

Inspect with errors.Is (sentinel) / errors.As (typed) — never err == ErrX or a type assertion once any layer wraps, or you get sentinel breakage (the comparison silently stops matching). (Go 1.13; errors.As target must be a pointer.)

Sentinel errors (var ErrNotFound = errors.New("not found")) for expected, comparable conditions that are part of your API contract — keep the set small and documented. Typed errors (a struct implementing error) when callers need fields (*PathError).

errors.Join(err1, err2) (Go 1.20) to aggregate independent failures (cleanup, validation) — replaces manual concatenation and most third-party multierror use.

Never swallow: no _ = f() on an error you care about; no empty if err != nil {}. Handle, wrap-and-return, or (deliberately, with a comment) ignore.

Add context at each layer, log once at the boundary. Wrapping at every level and logging at every level produces duplicate noise — return wrapped, log at the top.

Error strings: lowercase, no trailing punctuation (they get wrapped): "cannot parse %q".

Sources

go-errors

go-errors — Go error handling

Rules

Sources

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