Ionic framework TypeError:无法读取属性'；canDeactivate'；离子5中的空值

我无法在Ionic 5中实现canDeactivate guard。下面是我的代码

model.ts

export interface isDeactivatable {
    canDeactivate: () => Observable<boolean> | Promise<boolean> | boolean;
 }

离开

TestPage

时出现以下错误。 我曾尝试将

LeavePageGuard

作为提供者添加到应用程序模块和测试页面模块中，但仍然得到相同的错误

core.js:6014 ERROR Error: Uncaught (in promise): TypeError: Cannot read property 'canDeactivate' of null
TypeError: Cannot read property 'canDeactivate' of null
    at LeavePageGuard.canDeactivate (leave-page.guard.ts:15)
    at router.js:5543
    at Array.map (<anonymous>)
    at runCanDeactivate (router.js:5532)
    at MergeMapSubscriber.project (router.js:5349)
    at MergeMapSubscriber._tryNext (mergeMap.js:46)
    at MergeMapSubscriber._next (mergeMap.js:36)
    at MergeMapSubscriber.next (Subscriber.js:49)
    at Observable._subscribe (subscribeToArray.js:3)
    at Observable._trySubscribe (Observable.js:42)
    at resolvePromise (zone-evergreen.js:797)
    at resolvePromise (zone-evergreen.js:754)
    at zone-evergreen.js:858
    at ZoneDelegate.invokeTask (zone-evergreen.js:391)
    at Object.onInvokeTask (core.js:39680)
    at ZoneDelegate.invokeTask (zone-evergreen.js:390)
    at Zone.runTask (zone-evergreen.js:168)
    at drainMicroTaskQueue (zone-evergreen.js:559)
    at invokeTask (zone-evergreen.js:469)
    at ZoneTask.invoke (zone-evergreen.js:454)

core.js:6014错误：未捕获（承诺中）：TypeError:无法读取null的属性“canDeactivate”
TypeError:无法读取null的属性“canDeactivate”
在LeavePageGuard.canDeactivate（leavepage.guard.ts:15）
路由器：js:5543
在Array.map（）处
在runCanDeactivate（router.js:5532）
在MergeMapSubscriber.project（router.js:5349）
在MergeMapSubscriber.\u tryNext（mergeMap.js:46）
在MergeMapSubscriber.\u下一步（mergeMap.js:36）
在MergeMapSubscriber.next（Subscriber.js:49）
在可观察状态下。订阅（subscribeToArray.js:3）
在可观察的情况下。_尝试订阅（Observable.js:42）
at resolvePromise（zone evergreen.js:797）
at evergreen（zone evergreen.js:754）
常青区。js:858
在ZoneDelegate.invokeTask（zone everyver.js:391）
位于Object.onInvokeTask（core.js:39680）
在ZoneDelegate.invokeTask（zone evergreen.js:390）
在Zone.runTask（Zone everyver.js:168）
在drainMicroTaskQueue（zone evergreen.js:559）
在invokeTask（zone evergreen.js:469）
在ZoneTask.invoke（zone everyver.js:454）

解决方案非常简单，我找到了。问题在于延迟加载。大多数解决方案都不是针对延迟加载问题给出的

我将canDeativate防护从应用程序路由移动到该特定页面的模块路由。工作得很有魅力

test-rouring.module.ts

const routes: Routes = [
  {
    path: '',
    component: TestPage
    canDeactivate: [ LeavePageGuard ]
  }

const routes: Routes = [
  {
    path: '',
    component: HomePage,
    children:[
      {
        path: 'test',
        loadChildren: () => import('../pages/test/test.module').then( m => m.TestPageModule),
        canDeactivate: [LeavePageGuard]
      }
]
}
]

core.js:6014 ERROR Error: Uncaught (in promise): TypeError: Cannot read property 'canDeactivate' of null
TypeError: Cannot read property 'canDeactivate' of null
    at LeavePageGuard.canDeactivate (leave-page.guard.ts:15)
    at router.js:5543
    at Array.map (<anonymous>)
    at runCanDeactivate (router.js:5532)
    at MergeMapSubscriber.project (router.js:5349)
    at MergeMapSubscriber._tryNext (mergeMap.js:46)
    at MergeMapSubscriber._next (mergeMap.js:36)
    at MergeMapSubscriber.next (Subscriber.js:49)
    at Observable._subscribe (subscribeToArray.js:3)
    at Observable._trySubscribe (Observable.js:42)
    at resolvePromise (zone-evergreen.js:797)
    at resolvePromise (zone-evergreen.js:754)
    at zone-evergreen.js:858
    at ZoneDelegate.invokeTask (zone-evergreen.js:391)
    at Object.onInvokeTask (core.js:39680)
    at ZoneDelegate.invokeTask (zone-evergreen.js:390)
    at Zone.runTask (zone-evergreen.js:168)
    at drainMicroTaskQueue (zone-evergreen.js:559)
    at invokeTask (zone-evergreen.js:469)
    at ZoneTask.invoke (zone-evergreen.js:454)

const routes: Routes = [
  {
    path: '',
    component: TestPage
    canDeactivate: [ LeavePageGuard ]
  }