forgo.mount() typing not matching with behaviour

When trying to run the following code I got an unexpected error:

```tsx
import * as forgo from "forgo";

const App= () =>
new forgo.Component({
render() {
return

Tooltip

forgo.mount(document.getElementById("root"), );
```

`forgo.min.js:520 Uncaught Error: The container argument to the mount() function should be an HTML element.`

Now, because of the typing of `mount()`, this doesn't throw an error, though I'm not sure why.

```ts
export function mount(
forgoNode: ForgoNode,
container: Element | string | null
): RenderResult {
return forgoInstance.mount(forgoNode, container);
}
```

`null` however is never a valid container because `if (parentElement)` will always return `false`.