message: [Operational Tool] Use checked_add for auto validate feature.
  Closes:
diff: @@ -52,7 +52,9 @@ impl AutoValidate {
  }
  sleep(time::Duration::from_secs(self.sleep_interval));
  - time_slept += self.sleep_interval;
  + time_slept = time_slept
  + .checked_add(self.sleep_interval)
  + .expect("Integer overflow/underflow detected: unexpected amount of time slept!");
  }
  // Tried to find the execution result, but the transaction still hasn't been executed...
  