🎨 #38 存在しないcatIdが指定された場合は404を返すように変更

src/app/chat/[catId]/layout.tsx

@@ -1,6 +1,7 @@
-import { extractCatNameById, type CatId } from '@/features';
+import { extractCatNameById, isCatId, type CatId } from '@/features';
 import type { Metadata, ResolvingMetadata } from 'next';
 import { Noto_Sans_JP } from 'next/font/google';
+import { notFound } from 'next/navigation';
 import type { JSX, ReactNode } from 'react';
 
 const font = Noto_Sans_JP({
@@ -20,6 +21,10 @@ export const generateMetadata = async (
   // eslint-disable-next-line
   parent: ResolvingMetadata
 ): Promise<Metadata> => {
+  if (!isCatId(params.catId)) {
+    notFound();
+  }
+
   return {
     title: `AI Cat ${extractCatNameById(params.catId)}ちゃん🐱`,
     description: `ねこのAI（${extractCatNameById(

src/features/cat.ts

@@ -30,3 +30,9 @@ export const extractCatNameById = (catId: CatId): CatName => {
       throw new ExhaustiveError(catId);
   }
 };
+
+export const isCatId = (value: unknown): value is CatId => {
+  const result = catIds.find((element) => element === value);
+
+  return result !== undefined;
+};

src/features/index.ts

@@ -5,4 +5,4 @@ export type {
   FetchCatMessage,
 } from './cat';
 
-export { extractCatNameById } from './cat';
+export { extractCatNameById, isCatId } from './cat';