Disjunctions: Missing or invalid value when we have a default value in a disjunction.

We aren't handling the case when we set a default value in a disjunction. Looks like that its a global issue in all languages, ignoring the default or setting invalid value 🤷🏼 

Example:

```ts
layout?: *GridLayoutKind | RowsLayoutKind | AutoGridLayoutKind | TabsLayoutKind
```