message: agent: keep ticking the state-machine on errors
  This fixes a logic mistake that prevents the state-machine
  from progressing after the first error. Instead, the next tick
  should be scheduled regardless of the previous result.
diff: @@ -36,7 +36,7 @@ impl Handler<RefreshTick> for UpdateAgent {
  UpdateAgentState::_EndState => self.nop(),
  };
  - let update_machine = state_action.map(move |_r, actor, ctx| {
  + let update_machine = state_action.then(move |_r, actor, ctx| {
  if prev_state != actor.state {
  let now = chrono::Utc::now();
  actor.state_changed = now;
  @@ -44,6 +44,7 @@ impl Handler<RefreshTick> for UpdateAgent {
  } else {
  Self::tick_later(ctx, actor.refresh_period);
  }
  + actix::fut::ok(())
  });
  // Process state machine refresh ticks sequentially.
  