Check whether Mesos task labels are available

container/mesos/mesos_agent.go

@@ -113,9 +113,11 @@ func (s *state) fetchLabelsFromTask(exID string, labels map[string]string) error
 		}
 	}
 
+	if t.Labels != nil {
 		for _, l := range t.Labels.Labels {
 			labels[l.Key] = *l.Value
 		}
+	}
 
 	return nil
 }