fixed null pointer

frontend/src/pages/posts/[slug].astro

@@ -31,6 +31,7 @@ try {
 }
 
 function formatSlug(slug: string) {
+  if (!slug) return '';
   return slug
     .split('-')
     .map(word => word.charAt(0).toUpperCase() + word.slice(1))
@@ -46,9 +47,19 @@ function formatSlug(slug: string) {
         Back to list
       </a>
       {post && (
-        <h1 class="text-5xl font-extrabold text-mauve mt-4">
-          {formatSlug(post.slug)}
-        </h1>
+        <div class="flex justify-between items-start mt-4">
+          <h1 class="text-5xl font-extrabold text-mauve">
+            {formatSlug(post.slug)}
+          </h1>
+          <a 
+            href={`/admin/editor?edit=${post.slug}`} 
+            id="edit-btn"
+            class="hidden bg-surface0 hover:bg-surface1 text-blue px-4 py-2 rounded border border-surface1 transition-colors items-center gap-2"
+          >
+            <svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M17 3a2.85 2.83 0 1 1 4 4L7.5 20.5 2 22l1.5-5.5Z"/><path d="m15 5 4 4"/></svg>
+            Edit
+          </a>
+        </div>
       )}
     </header>
 
@@ -73,22 +84,3 @@ function formatSlug(slug: string) {
     }
   </script>
 </Layout>
-1.5-5.5Z"/><path d="m15 5 4 4"/></svg>
-            Edit
-          </a>
-        </div>
-      )}
-    </header>
-
-    {error && (
-      <div class="text-red text-center py-12">
-        <h2 class="text-2xl font-bold mb-4">{error}</h2>
-        <a href="/" class="text-blue underline">Return home</a>
-      </div>
-    )}
-
-    {post && (
-      <div class="prose prose-invert max-w-none" set:html={html} />
-    )}
-  </article>
-</Layout>