err equals err code example

Example 1: golang create error

// simple string-based error
err1 := errors.New("math: square root of negative number")

Example 2: go error handling

func doStuff() (int, error) {
}

func main() {
    result, err := doStuff()
    if err != nil {
        // handle error
    } else {
        // all is good, use result
    }
}