this allows testing error paths in code:
Pass an `error` type as the Value, it will be reflect-checked if it is
an error, and be returned
```golang
as, restoreAsk := prompt.InitAskStubber()
defer restoreAsk()
as.Stub([]*prompt.QuestionStub{
{
Name: "assignee",
Value: errors.New("meant to fail"),
},
})
```
Example code that will benefit:
```golang
var confirmAnswers []string
err := prompt.MultiSelect(&confirmAnswers, "metadata", "Which metadata types to add?", options)
if err != nil {
return nil, fmt.Errorf("could not prompt: %w", err)
}
```