How do get query string parameter in sveltekit?

I'm trying to the /login?ref=/some/path parameter to redirect to after login:

const ref = $page.url.searchParams.get('ref') || '/dashboard';

However I get this error:

TypeError: Cannot read properties of undefined (reading 'searchParams')

The above solutions won't work. This is the new way:

export async function load({ params, url }) {
    let lang = url.searchParams.get('lang');
    let q = url.searchParams.get('q');
    return { lang, q };
}

Then, please reach it as this:

import { page } from '$app/stores';
$page.data.q

Thanks to Richard this is much better than acknowledging export var lang in each page