Svelte : stores support #132

I just tried to use svelte stores and I had a problem in stores.js :

import { writable } from 'svelte/store';

^^^^^^

SyntaxError: Cannot use import statement outside a module

The same code seems to work in Rollup.

For your information the given code can be found on this REPL: https://svelte.dev/repl/a551a40e90374fd2861255c957123af2?version=3.22.2

Do you know what's going on there ?