Correct to throw error if not a music file

src/app/api/upload/route.ts

@@ -8,7 +8,7 @@ const MUSIC_DIR = '/app/music';
 export async function POST(req: NextRequest) {
   const formData = await req.formData();
   const file = formData.get('file') as File;
-  if (checkIfMusicFile(file.name)) {
+  if (!checkIfMusicFile(file.name)) {
     return NextResponse.json(
       { error: 'Only music files are allowed to be uploaded' },
       { status: 400 },