Include registration error in the log (#657)

* Include registration error in the log

* remove chatty debug log

this will show in the logs every 5 seconds as debug (not even trace) which leads to a lot of noise

periodic_task_manager.go

@@ -172,8 +172,8 @@ func (mgr *PeriodicTaskManager) add(configs []*PeriodicTaskConfig) {
 	for _, c := range configs {
 		entryID, err := mgr.s.Register(c.Cronspec, c.Task, c.Opts...)
 		if err != nil {
-			mgr.s.logger.Errorf("Failed to register periodic task: cronspec=%q task=%q",
-				c.Cronspec, c.Task.Type())
+			mgr.s.logger.Errorf("Failed to register periodic task: cronspec=%q task=%q err=%v",
+				c.Cronspec, c.Task.Type(), err)
 			continue
 		}
 		mgr.m[c.hash()] = entryID

scheduler.go

@@ -334,7 +334,6 @@ func (s *Scheduler) beat() {
 		}
 		entries = append(entries, e)
 	}
-	s.logger.Debugf("Writing entries %v", entries)
 	if err := s.rdb.WriteSchedulerEntries(s.id, entries, s.heartbeatInterval*2); err != nil {
 		s.logger.Warnf("Scheduler could not write heartbeat data: %v", err)
 	}