I tried ¯\_(ツ)_/¯

result.go

package main

import (
        "errors"
        "fmt"
        "reflect"
        "time"
)

type Result struct {
        value interface{}
        err   error
}

func (r Result) Error() error {
        return r.err
}

func (r Result) Value() interface{} {
        return r.value
}

func (r Result) IsValueOfType(cmp interface{}) bool {
        return reflect.TypeOf(r.value) == reflect.TypeOf(cmp)
}

func (r Result) WithError(err error) Result {
        r.err = err
        return r
}

func (r Result) WithValue(val interface{}) Result {
        r.value = val
        return r
}

type SomeData struct {
        Name string
        Date time.Time
}

func (s *SomeData) DoThing() {
        fmt.Printf("Doing a thing for %s\n", s.Name)
}

func GetData() Result {
        return Result{}.WithValue(&SomeData{
                Name: "Some Data",
                Date: time.Now(),
        })
}

func GetDataError() Result {
        return Result{}.WithError(errors.New("There was a problem"))
}

func main() {
        var res Result

        res = GetData()
        if res.Error() != nil {
                panic(res.Error())
        }

        if res.IsValueOfType(&SomeData{}) {
                value := res.Value().(*SomeData)
                value.DoThing()
        }

        fmt.Printf("%#v\n", res.Value())

        res = GetDataError()
        if res.Error() != nil {
                panic(res.Error())
        }
}