message: Fixing error message
diff: @@ -343,8 +343,8 @@ impl Reactor for MultiStageTestReactor {
  .values()
  .sum::<usize>(),
  0,
  - "before transitioning from joiner to validator, \
  - there should be no unprocessed events"
  + "before transitioning from initializer to joiner, there should be no \
  + unprocessed events"
  );
  let joiner_scheduler = utils::leak(Scheduler::new(QueueKind::weights()));
  