stage 7 attempt 3 (add 404)

src/main.rs

@@ -70,12 +70,12 @@ async fn process (mut stream: TcpStream, args: A) -> Result<()> {
         p if p.starts_with("/files/") => {
             let path = args.directory.join(p.trim_start_matches("/files/"));
             let mut buf = vec![];
-            let mut f = File::open(path).await?;
-
-
+            if let Ok(mut f) = File::open(path).await {
                 let _ = f.read_to_end(&mut buf).await;
-
                 Response::OctetStream(buf)
+            } else {
+                Response::_404
+            }
         },
         _ => Response::_404,
     };