Svelte error : 'product' is not a store with a subscribe method with shopify api

<script> import { getProduct } from '../lib/store'; const productId = 'a'; const product = getProduct(productId); $: [login to view URL]($product); let quantity = 0; let price = 0; let total = 0; $: quantity = quantity < 1 ? 1 : quantity; $: options = $[login to view URL]((items) => { let list = {}; [login to view URL] = [login to view URL]; [login to view URL] = [login to view URL][0].value; [login to view URL] = [login to view URL][1].value; [login to view URL] = [login to view URL]; return list; }); $: [login to view URL](options); let selected_color; let selected_size; let selected; $: selected = [login to view URL](function (elem) { return [login to view URL] === selected_size && [login to view URL] === selected_color; }); $: if (selected_color && selected_size) { total = (quantity * selected[0].price).toFixed(2); } $: if (selected_color && selected_size) { [login to view URL]('selected variant ID : ' + selected[0].id); //alert('selected variant ID : '+ selected[0].id) } </script> {#await product} <h1> {$[login to view URL]} </h1> <img src={$[login to view URL][0].[login to view URL]} alt="product" style="width:350px;border-radius:15%;" /> <br /><br /> <h3>Color</h3> {#each $[login to view URL][0].values as option} <label> <input bind:group={selected_color} selected="fa" type="radio" name={option} value={option} /> {option} </label> {/each} <h3>Size</h3> {#each $[login to view URL][1].values as option} <label> <input bind:group={selected_size} selected="fa" type="radio" name={option} value={option} /> {option} </label> {/each} {#if selected_color}{selected_color} / {/if} {#if selected_size}{selected_size}{/if} <br /><br /> <label for="quantity">Quantity</label> <input name="quantity" bind:value={quantity} style="width:150px;" type="number" /> <p> price : $ {total} </p> {#if selected_color && selected_size} <p> Selected variant ID {selected[0].id} </p> {/if} {/await} This is my API function [login to view URL] export async function getProduct(handle) { const query = ` { productByHandle(handle: "${handle}") { collections(first: 1) { edges { node { products(first: 5) { edges { node { priceRange { minVariantPrice { amount } } handle title description id images(first: 5) { edges { node { originalSrc altText } } } } } } } } } id title handle description images(first: 5) { edges { node { originalSrc altText } } } options { name values id } variants(first: 25) { edges { node { selectedOptions { name value } } } } } }`; const response = await ShopifyData(query); const product = [login to view URL] ? [login to view URL] : []; return product; }