Angular HTTP get request is not working in ngOnInit

I am trying to fetch the data from backend API on component load.

API call in service file

  getFiles(): Observable<any> {
    return this.httpClient.get<any>('http://localhost:5000/api/file');
  }

Subscribing to that service in component inside OnInit

  ngOnInit(): void {
    this.postDataService.getFiles().subscribe( data => {
      console.log('test', data);
    });
  }

Its giving below response (200). I am not getting any error

code: "EINVALIDSTATE"
message: "Requests can only be made in the LoggedIn state, not the SentClientRequest state"

If I call the same service on (click) it works fine.

 testClick(): void {
    this.postDataService.getFiles().subscribe( data => {
      console.log('test', data);
    });
  }

Is there any issue with calling service in ngOnInit. How can make it work?

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EDIT

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After so much of troubleshooting I found that its giving error when I try to load the child routes directly. If I load home page and then click on link to navigate to any component then this api call works fine.