memory leak in adapter node with unresolved promises

Describe the bug

Rendering a page that depends on a never-solving promise leaks memory.

Svelte seems to keep handlers around for the resolution of promises even after the page has been fully rendered and served to the client, preventing the js engine from freeing the associated memory.

Reproduction

https://github.com/lovasoa/sveltekit-memory-leak-bugreport

+page.svelte

<script>
    import c from './const';
</script>

{#await c.waitForMe()}
    <p>loading...</p>
{:then x}
    <p>loaded {x}!</p>
{:catch error}
    <p style="color: red">{error.message}</p>
{/await}

const.js

class MyClass {
    constructor() {
        this.x = neverSolve();
    }
    async waitForMe() {
        const x = await this.x;
        return x+1;
    }
}

function neverSolve() {
    return new Promise(()=>{});
}

export default new MyClass;

Logs

No response

System Info

System:
    OS: Linux 6.2 Ubuntu 22.04.3 LTS 22.04.3 LTS (Jammy Jellyfish)
    CPU: (8) x64 11th Gen Intel(R) Core(TM) i7-11390H @ 3.40GHz
    Memory: 1.03 GB / 15.36 GB
    Container: Yes
    Shell: 5.1.16 - /bin/bash
  Binaries:
    Node: 16.20.2 - /usr/bin/node
    Yarn: 1.22.19 - /usr/bin/yarn
    npm: 8.19.4 - /usr/bin/npm
    pnpm: 8.6.3 - /usr/bin/pnpm
  Browsers:
    Chrome: 116.0.5845.187
  npmPackages:
    svelte: ^4.0.5 => 4.2.0

Severity

annoyance

Start with the linked sveltekit-memory-leak-bugreport reproduction, especially +page.svelte and const.js, and run it with the reported Node setup. Trace the adapter's server-side rendering of the unresolved promise and verify that rendered pages no longer retain promise-resolution handlers or the associated memory.