inlineErrorAs.go

package main

import (
	"errors"
	"fmt"
)

func main() {
	err := wrong()
	fmt.Println(As[*Aerror](err))
}

func wrong() error { return &Aerror{} }

func As[T error](err error) (t T) {
	target := new(T)

	if errors.As(err, target) {
		return *target
	}

	return
}

type Aerror struct{}

func (a *Aerror) Error() string { return "duck" }