Describe the bug

In the snippet below, I can't use $ to access the contents of store. I'm not sure if this is a Svelte or a TypeScript problem, I suspect Svelte:

<script>
import type { Writable } from "svelte/store";

export let store: Writable<string[]> | null = null;

  if (store) {
    $store.length
  }
</script>

TypeScript tells me that "Property 'length' does not exist on type 'never'.", even though the type of $store should be string[] inside the if block.

Expected Behavior
TypeScript infers the type of $store as string[] inside the if block.

Actual Behavior
TypeScript infers the type of $store as null inside the if block.

Reproduction

Copying the script above should be enough

Logs

No response

System Info

System:
    OS: Windows 10 10.0.19045
    CPU: (12) x64 AMD Ryzen 5 5600X 6-Core Processor
    Memory: 16.32 GB / 31.91 GB
  Binaries:
    Node: 16.13.0 - C:\Program Files\nodejs\node.EXE
    npm: 8.4.1 - ~\node_modules\.bin\npm.CMD
  Browsers:
    Edge: Spartan (44.19041.1266.0), Chromium (111.0.1661.44)    
  npmPackages:
    rollup: ^2.3.4 => 2.79.1
    svelte: ^3.0.0 => 3.55.1

Severity

annoyance