TypeError: Cannot read property 'canDeactivate' of null in IONIC 5

Question

I am unable to implement canDeactivate guard in Ionic 5. Following are my code.

model.ts

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

leave-page.guard.ts

export class LeavePageGuard implements CanDeactivate<isDeactivatable>{
  canDeactivate(
    component: isDeactivatable
  ): Observable<boolean> | Promise<boolean> | boolean {
    console.log('LeavePageGuard');
    return component.canDeactivate();
  }

}

test-page.ts

export class TestPage implements OnInit, isDeactivatable{
      canDeactivate(): Observable<boolean> | Promise<boolean> | boolean {
        console.log('canDeactivate in TestPage');
        return true;
      }
}

home-routing.Module.ts

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

I am getting the following error when leaving TestPage. I have tried adding LeavePageGuard in App Module and in TestPage Module as a provider but still getting the same error.

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)

Answer 1

The solution was very easy and I found it here. The issue was with lazy loading. The majority of the solutions are given not for Lazy loading issue.

I moved the canDeativate guard from app routing to that particular page's module routing. Worked like a charm.

test-rouring.module.ts

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