[core] Do not crash when receiving update on nonexistent task

Author: teo

core/task/manager.go

@@ -686,13 +686,14 @@ func (m *Manager) configureTasks(envId uid.ID, tasks Tasks) error {
 				}
 
 				taskDescription = fmt.Sprintf("task '%s' on %s (id %s, name %s) failed with error: %s", tciValue, task.GetHostname(), task.GetTaskId(), task.GetName(), v.Error())
+				if task.GetTraits().Critical == true || task.parent.GetTaskTraits().Critical == true {
+					taskCriticalErrors = append(taskCriticalErrors, taskDescription)
+				} else {
+					taskNonCriticalErrors = append(taskNonCriticalErrors, taskDescription)
+				}
 			} else {
 				taskDescription = fmt.Sprintf("unknown task (id %s) failed with error: %s", k.TaskId.Value, v.Error())
-			}
-			if task.GetTraits().Critical == true || task.parent.GetTaskTraits().Critical == true {
 				taskCriticalErrors = append(taskCriticalErrors, taskDescription)
-			} else {
-				taskNonCriticalErrors = append(taskNonCriticalErrors, taskDescription)
 			}
 			i++
 		}