language-tools: Typescript control flow inside if/{#if} not working when using $store

When you have a store defined as follows:

import { readable, Readable } from "svelte/store"

const post: Readable<Post|null> = readable(null, /* some code that loads the post asynchronously */)

And then in your template you write:

<h1>{$post.title}</h1>

Then the typescript checker rightly complains Object is possibly 'null'. Then I was hoping that I could make that error disappear by doing this:

{#if $post !== null}
    <h1>{$post.title}</h1>
{/if}

But that has no effect whatsoever. Which kind of makes sense. I understand that typescript may not understand that that is an if-statement.

I can imagine that this would actually not be trivial to implement, but I don’t know, it would be really nice.