message: change unwrap for expect
diff: @@ -120,7 +120,7 @@ where
  /// Crank the specified runner once, returning the number of events processed.
  pub async fn crank<RNG: Rng + ?Sized>(&mut self, node_id: &R::NodeId, rng: &mut RNG) -> usize {
  - let runner = self.nodes.get_mut(node_id).unwrap();
  + let runner = self.nodes.get_mut(node_id).expect("should find node");
  let node_id = runner.reactor().node_id();
  let span = tracing::error_span!("crank", node_id = %node_id);
  