SvelteKit and undefined readyState

[jaclas]

I try to use this library, but I get error in browser:

Uncaught (in promise) TypeError: Cannot read properties of undefined (reading 'readyState')
at Object.set (index.mjs:80:18)

My code:

const initialValue = { };

if (browser) {
    const myStore = websocketStore("ws://localhost:3000/foo", initialValue);
    myStore.set({
        content: "to be saved",
        other_values: "all"
    });
}

I use latest Svelte's:

❯ npm list
epsvelte@0.0.1 /home/jacek/storage/developSSD/epsvelte
├── @sveltejs/kit@1.0.0-next.342
├── svelte-websocket-store@1.1.24
└── svelte@3.48.0