Apply clippy suggestion

src/bin/main.rs

@@ -20,12 +20,10 @@ async fn main() -> Result<(), BoxError> {
                 }
                 #[cfg(not(target_os = "linux"))]
                 log::error!("Your platform doesn't support unprivileged namespaces");
-            } else {
-                if let Err(err) = tun2proxy::desktop_run_async(args, shutdown_token).await {
+            } else if let Err(err) = tun2proxy::desktop_run_async(args, shutdown_token).await {
                 log::error!("main loop error: {}", err);
             }
         }
-        }
     });
 
     ctrlc2::set_async_handler(async move {