feat(#29): Remove checkout button when not signed in

src/routes/checkout/+page.svelte

@@ -3,6 +3,10 @@
 	import { basket, type Basket, type Item } from '$lib/stores/basket.js';
 	import BasketItem from '$lib/components/checkout/BasketItem.svelte';
 
+	export let data;
+	let { supabase, session, url } = data;
+	$: ({ supabase, session, url } = data);
+
 	let localBasket: Basket;
 	const unsubscribe = basket.subscribe((value) => {
 		localBasket = value;
@@ -101,6 +105,7 @@
 						/>
 					</svg>
 				</a>
+				{#if session?.user !== undefined}
 					<button
 						type="submit"
 						class="btn btn-primary"
@@ -123,6 +128,9 @@
 							/>
 						</svg>
 					</button>
+				{:else}
+					<p>You must sign in to checkout</p>
+				{/if}
 			</div>
 		</form>
 	</div>