An example, the json package specifies a SyntaxError type that the json.Decode function returns when it encounters a syntax error parsing a JSON blob.

JsonSyntaxError.go

if err := dec.Decode(&val); err != nil {
    if serr, ok := err.(*json.SyntaxError); ok {
        line, col := findLine(f, serr.Offset)
        return fmt.Errorf("%s:%d:%d: %v", f.Name(), line, col, err)
    }
    return err
}