title: page.params is undefined in SvelteKit
body: <p>I'm new in using SvelteKit. I read the docs (I'm doing my best to follow along and follow what's there to make my website work).</p>
  <p>In my <code>src &gt; routes &gt; posts &gt; [postId].svelte</code>:</p>
  <pre><code>&lt;script&gt;
      // http://localhost:3000/posts/[postId]
  
      import PostDetails from '../../components/pages/PostDetails.svelte';
  &lt;/script&gt;
  
  &lt;PostDetails /&gt;
  </code></pre>
  <p>In my <code>src &gt; components &gt; pages &gt; PostDetail.svelte</code>:</p>
  <pre><code>&lt;script&gt;
     import { page } from '$app/stores';
  
     console.log({ page });
     console.log('page.params', page.params);
  &lt;/script&gt;
  
  &lt;h1&gt;Post Title&lt;/h1&gt;
  </code></pre>
  <p>I want to get the <code>page.params.postId</code> but it doesn't work. So I've decided to log the value of <code>page</code> and <code>page.params</code> on the console:</p>
  <p><a href="https://i.stack.imgur.com/m6g3X.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/m6g3X.png" alt="enter image description here" /></a></p>
  <p>As stated <a href="https://kit.svelte.dev/docs#loading-input-page" rel="nofollow noreferrer">in the docs</a>, I was expecting to get <code>{ host, path, params, query }</code> from this <code>page</code> object. But I got nothing but a <code>subscribe</code> function. What am I doing wrong? Please help.</p>