/// use std::panic;
///
/// panic::set_hook(Box::new(|panic_info| {
-/// println!("panic occurred: {:?}", panic_info.payload().downcast_ref::<&str>().unwrap());
+/// if let Some(s) = panic_info.payload().downcast_ref::<&str>() {
+/// println!("panic occurred: {:?}", s);
+/// } else {
+/// println!("panic occurred");
+/// }
/// }));
///
/// panic!("Normal panic");