title: Svelte store subscribed function should not be invoked on subscription
body: <p>I don't understand this. I am trying to subscribe to a svelte store. But the closure function which is being passed to <em><strong>subscribe</strong></em> is being immediately invoked. Even though the value of the store hasn't changed.</p>
  <p><a href="https://svelte.dev/repl/926bb8de12964f60959cb9607b5bfef4?version=3.35.0" rel="nofollow noreferrer">Here's a svelte REPL <strong>example</strong></a></p>
  <p>with the following code:</p>
  <pre class="lang-js prettyprint-override"><code>&lt;script&gt;
      import { onDestroy } from 'svelte';
      import { writable } from 'svelte/store';
      
      const store = writable({ givenName: '', familyName: '' });
      
      const unsubscribe = store.subscribe( state =&gt; {
      console.log('This function shouldn\'t have been invoked on subscription.');
      });
      onDestroy(unsubscribe);
  &lt;/script&gt;
  
  &lt;h1&gt;
      Please check the console output ...
  &lt;/h1&gt;
  </code></pre>
  <p>IMHO, the closure function should be fired on change and not on subscriptionn or is there something I am missing?</p>