feat: Add error page

src/routes/+error.svelte

@@ -0,0 +1,15 @@
+<script>
+	import { page } from '$app/stores'
+</script>
+
+<div class="error">
+	<h1>{$page.status}: {$page.error?.message}</h1>
+</div>
+
+<style>
+	.error {
+		height: 50vh;
+		display: grid;
+		place-content: center;
+	}
+</style>

src/routes/+layout.svelte

@@ -14,12 +14,13 @@
 		</div>
 		<div id="content">
 			<slot />
+			<Footer />
 		</div>
 	</div>
 {:else}
 	<slot />
-{/if}
 	<Footer />
+{/if}
 
 <style>
 	:global(.navbar-link) {