$ cargo check
    Checking hello v0.1.0 (file:///projects/hello)
error[E0507]: cannot move out of `worker.thread` which is behind a mutable reference
  --> src/lib.rs:52:13
   |
52 |             worker.thread.join().unwrap();
   |             ^^^^^^^^^^^^^ move occurs because `worker.thread` has type `JoinHandle<()>`, which does not implement the `Copy` trait

For more information about this error, try `rustc --explain E0507`.
error: could not compile `hello` due to previous error