panic on top-level error

src/main.rs

@@ -279,11 +279,10 @@ fn main() {
         let workers: Vec<_> = (0..cpus)
             .map(|_| s.spawn(|_| {
                 res.worker_loop()
-                    .map_err(|e| println!("{}", e))
             }))
             .collect();
         for worker in workers.into_iter() {
-            worker.join().expect("worker").unwrap();
+            worker.join().expect("worker join").expect("worker");
         }
     }).unwrap();
 }