Angular Unit Test Error: 1 component threw errors during cleanup at...

I'm testing a component which has injected a service. The problem that as I saw, it's not entering the ngOnDestroy(). I ask explicity the test to destroy() after every test I get error message that "cannot unsubscribe from undefined". What could be the problem?

Component:

//...
subscription: Subscription;

constructor(private readonly router: Router,
private dialog: MatDialog,
private readonly carService: carService) {
}

ngOnInit(): void {
this.cars$ = this.carService.getCars();
this.subscription= this.cars$.subscribe(cars=> {
this.cars= cars;
});
}

ngOnDestroy() {
this.subscription.unsubscribe();
}


Test:

//...
beforeEach(async () => {
await TestBed.configureTestingModule({

providers: [
{provide: MatDialog, useClass: dialogMock},
{provide: Router, useValue: routerMock},
{provide: APP_BASE_HREF, useValue: '/cars'}
]
}).compileComponents();

component = TestBed.createComponent(CarComponent).componentInstance;
service = TestBed.inject(CarService);
service.setProjects([firstCar, secondCar]);
component.ngOnInit();
});

it('test', () => {
expect(component).toBeInstanceOf(CarComponent);
});

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