Context类型错误，报错401“The context must be a valid Context”

import { AbilityConstant, UIAbility, Want } from '@kit.AbilityKit'; 
export default class EntryAbility extends UIAbility { 
  onCreate(want: Want, launchParam: AbilityConstant.LaunchParam) { 
    let uiAbilityContext = this.context; 
    ... 
  } 
}