fix not found page back button

custom/basic-call/pages/not-found.js

@@ -1,10 +1,13 @@
 import React from 'react';
 import MessageCard from '@custom/shared/components/MessageCard';
+import { useRouter } from 'next/router';
 
 export default function RoomNotFound() {
+  const router = useRouter();
+
   return (
     <div className="not-found">
-      <MessageCard error header="Room not found">
+      <MessageCard error header="Room not found" onBack={() => router.push('/')}>
         The room you are trying to join does not exist. Have you created the
         room using the Daily REST API or the dashboard?
       </MessageCard>