astro/packages/renderers/svelte/client.js

import SvelteWrapper from './Wrapper.svelte';

export default (target) => {
  return (component, props, children) => {
    try {
      new SvelteWrapper({
        target,
        props: { __astro_component: component, __astro_children: children, ...props },
        hydrate: true,
      }); 
    } catch (e) {}
  }
}