fix(videos): incorrect return type on MediaType

frontend/src/App.tsx

@@ -1,4 +1,4 @@
-// App.jsx
+ // App.jsx
 import { BrowserRouter as Router, Routes, Route } from 'react-router-dom';
 import MainLayout from './layouts/MainLayout';
 import ClipUpload from './pages/ClipUpload';

frontend/src/pages/MediaPlayer.tsx

@@ -17,7 +17,7 @@ type MediaPlayerProps = {
     /** Fetches the raw video blob for the given id. */
     fetchBlob: (id: string) => Promise<Blob>,
     /** Fetches the media metadata for the given id. */
-    fetchDetails: (id: string) => Promise<MediaItem>,
+    fetchDetails: (id: string) => Promise<MediaItem | null>,
 };
 
 const MediaPlayer = ({ noun, fetchBlob, fetchDetails }: MediaPlayerProps) => {