Angular Component ViewChild object is null

Question

I have below code written in Angular 10 with Rx.js and Nxdev. I am getting object eventInfoCardStep2 & eventInfoCardStep3 as null due to which further code of downloading excel does not work. If i comment below error giving lines then file get download but modal spinner does not stop. this.eventInfoCardStep2.displaySpinner = false; this.eventInfoCardStep3.displaySpinner = false;

export class EventInfoCardComponent
  extends AbstractV2Component
  implements OnChanges {
  @Input() assetEventDetails: AssetEvent;
  showEventInfoCard = true;
  uploadedFileNameList: string[] = [];
  uploadedFileList: TableDataRow[] = [];
  eventBulkTransactionId = '';
  displaySpinner = false;

  constructor(
    private store: Store<fromRoot.State>,
    private stringProcessService: StringProcessService
  ) {
    super();
  }
}  


import { Actions, ofType } from '@ngrx/effects';
import { filter, takeUntil } from 'rxjs/operators';
import { Subscription } from 'rxjs';

export class EventStepperComponent
  extends AbstractV2Component
  implements OnInit, OnDestroy {

    @ViewChild('eventInfoCardStep2')
    eventInfoCardStep2: EventInfoCardComponent;
    @ViewChild('eventInfoCardStep3', { static: false })
    eventInfoCardStep3: EventInfoCardComponent;

 this.eventCardSubscriptions = [];

    const subs1: Subscription = this.actions$
      .pipe(
        filter(
          (data) =>
            data.type ===
            assetEventActions.AssetEventActionType
              .DOWNLOAD_ASSET_EVENT_ATTACHMENT_FROMCARD_SUCCESS
        ),
        takeUntil(this.unsubscribe$)
      )
      .subscribe(
        (
          action: assetEventActions.DownloadAssetEventAttachmentFromCardSuccess
        ) => {
          this.displaySpinner = false;
          this.eventInfoCardStep2.displaySpinner = false;
          this.eventInfoCardStep3.displaySpinner = false;
          if (action.response.size !== 0) {
            const blob = new Blob([action.response], {
              type: 'application/octatestream',
            });
            fileSaver.saveAs(blob, action.fileName.trim());
          }
        }
      );
}