Array prop with a union type including undefined causes an error

[samtjo]

Hi @merceyz - great library! It's been really handy on the project I work on.

We have come across this bug, take a look at this simple example component:

import React from "react";

interface ExampleProps {
  arrayProp: Array<string | undefined>;
}

const Example = ({ arrayProp }: ExampleProps) => {
  return arrayProp && <div>Example</div>;
};

export default Example;

The key part for this, is the arrayProp type is a union type that can be undefined. It causes the following error when calling the generate function from this package:

I think either the t.isUnionNode check needs to be able to handle one of the types in a union being undefined or we need a catch all if (t.isUndefinedNode(node)) check to return the correct type.