Navigation 在栈底页面时，无法侧滑返回桌面

.onBackPressed(() => { 
  console.log(`cwq PF- onBackPressed ${this.constructor.name}`) 
  let stackSize = this.mainStack.size(); 
  if (stackSize === 1) { 
    console.log('cwq stack size is ' + stackSize) 
    let eventData: emitter.EventData = { 
      data: { 
        "id": 1, 
      } 
    }; 
    let innerEvent: emitter.InnerEvent = { 
      eventId: 1, 
      priority: emitter.EventPriority.HIGH 
    }; 
    emitter.emit(innerEvent, eventData); 
  } 
  return false; 
})

let innerEvent: emitter.InnerEvent = { 
  eventId: 1 
}; 
 
// 收到eventId为1的事件后执行回调函数 
emitter.on(innerEvent, () => { 
  console.log('cwq on innerEvent call back') 
  // this.onBackPress(); 
  router.back() 
});