[Bug]

[brenley]

Using Transform option with Select and returning another interface causes Cleanup to panic.

e.g. given:

err := survey.Ask([]*survey.Question{{
        Name: "FavoriteFruit",
        Prompt: &survey.Select{
            Message: "What is your favorite fruit?",
            Default: "banana",
            Options: []string{"apple", "banana", "grape"},
        },
        Transform: func(ans interface{}) interface{} {
            switch ans := ans.(type) {
            case core.OptionAnswer:
                return FruitFromString(ans.Value)
            }
            return nil
        },
    },
}}, &surveyData)

https://github.com/AlecAivazis/survey/blob/e64d9b644fb7d85d69cd3e33a92a43ee706c1b6f/select.go#L323

panic: interface conversion: interface {} is Fruit, not core.OptionAnswer

goroutine 1 [running]:
github.com/AlecAivazis/survey/v2.(*Select).Cleanup(0xc000446240, 0xc0003f2468, 0x1ab1240, 0xc00040cc38, 0x1, 0xc000428238)

[AlecAivazis]

Hey @brenley!

Let me start by admitting this part of the API is slightly confusing. The issue you are running into is caused by your return value in Transform. The Transform of a Select prompt can return string, int, or survey.OptionAnswer.

Unfortunately, this forces you to serialize and deserialize the struct you want but at the moment that's how things are structured. For more information on this you can see #105