Error Handling Patterns We Actually Use

Wrapping with %w, sentinel errors, errors.As for types — and when a panic is genuinely the right call.

Kampala Gophers Team31 Aug 20263 min read

if err != nil is not boilerplate; it's where your program decides what failure means.

main.go

var ErrInsufficientFunds = errors.New("insufficient funds")

func (w *Wallet) Withdraw(amount int64) error {
	if amount > w.balance {
		return fmt.Errorf("withdraw %d: %w", amount, ErrInsufficientFunds)
	}
	w.balance -= amount
	return nil
}

if errors.Is(err, ErrInsufficientFunds) {
	// show a friendly message, don't page anyone
}

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