message: Fix credit calculation
diff: @@ -115,11 +115,10 @@ void inbound_path::emit_ack_batch(local_actor* self, int32_t queued_items,
  timespan cycle, timespan complexity) {
  CAF_LOG_TRACE(CAF_ARG(slots) << CAF_ARG(queued_items) << CAF_ARG(cycle)
  << CAF_ARG(complexity));
  + CAF_IGNORE_UNUSED(queued_items);
  auto x = stats.calculate(cycle, complexity);
  // Hand out enough credit to fill our queue for 2 cycles.
  - auto credit = std::max((x.max_throughput * 2)
  - - (assigned_credit + queued_items),
  - 0);
  + auto credit = std::max((x.max_throughput * 2) - assigned_credit, 0);
  // Protect against overflow on `assigned_credit`.
  auto max_new_credit = std::numeric_limits<int32_t>::max() - assigned_credit;
  // The manager can restrict or adjust the amount of credit.
  