add: 見出しがない時は表示しないように

src/routes/(DefaultStyle)/post/[slug]/+page.svelte

@@ -84,9 +84,11 @@
 			<div>
 				<Share share={{url:`${baseURL}/post/${data.id}`, title:data.metadata.title}} />
 			</div>
+			{#if data.heading.length!=0}
 				<div id='toc'>
 					<Toc toclist={data.heading}></Toc>
 				</div>
+			{/if}
 			<div class="mi-posts js">
 				<iframe src="https://mi.moris.day/embed/user-timeline/9w7bhjzt2b5z0001?maxHeight=300&rounded=false&border=false" title="moris's posts" data-misskey-embed-id="v1_fe3a992c-ac63-42f9-9339-d657fe56462f" loading="lazy" referrerpolicy="strict-origin-when-cross-origin" style="width:100%; height:300px; border:solid #8884 1px; border-radius:8px; box-sizing:border-box"></iframe>
 			</div>