app/tags/[tag]/page.tsx

@@ -6,6 +6,7 @@ import { allBlogs } from 'contentlayer/generated'
 import tagData from 'app/tag-data.json'
 import { genPageMetadata } from 'app/seo'
 import { Metadata } from 'next'
+import { notFound } from 'next/navigation'
 
 export async function generateMetadata({ params }: { params: { tag: string } }): Promise<Metadata> {
   const tag = decodeURI(params.tag)
@@ -37,5 +38,8 @@ export default function TagPage({ params }: { params: { tag: string } }) {
   const filteredPosts = allCoreContent(
     sortPosts(allBlogs.filter((post) => post.tags && post.tags.map((t) => slug(t)).includes(tag)))
   )
+  if (filteredPosts.length === 0) {
+    return notFound()
+  }
   return <ListLayout posts={filteredPosts} title={title} />
 }