Losing Prev URL with Angular Router Events

Question

Based on my research i found some code that worked or at least I thought so. I am using angular 11 and need to capture the previous url so I can route back to it. The below code gets the previous url most of the time but not always, and I set it as a variable. But then when user clicks the back error and calls my goBack function it goes always to my /home which is set as the default route if routes don't exist. So since i seem to get the prev route there mist be something in my code that resets the previousUrl as an empty string and prevents it to work. Do I need to filter additional events to prevent this from happening ?

import {Component, OnDestroy, OnInit} from '@angular/core';
import {ActivatedRoute, Router, RoutesRecognized} from '@angular/router';
import {map, takeWhile} from 'rxjs/operators';
import {ToasterService} from 'angular2-toaster';
import {Location} from '@angular/common';
import {Base64Service} from '../../../../../services/base64.service';
import {FarmService} from '../../../../../services/farm/farm.service';
import {IFarmMaster} from '../../../../../models/farm';
import {Observable} from 'rxjs';

import { filter, pairwise } from 'rxjs/operators';

@Component({
    selector: 'app-farm-master-wrapper',
    templateUrl: './farm-master-wrapper.component.html',
    styleUrls: ['./farm-master-wrapper.component.scss'],
})
export class FarmMasterWrapperComponent implements OnInit, OnDestroy {

    farm: IFarmMaster;
    private state$: Observable<object>;
    alive = true;
    previousUrl: string = "";

    constructor(
        protected route: ActivatedRoute,
        private farmService: FarmService,
        private toasterService: ToasterService,
        private base64Service: Base64Service,
        private location: Location,
        private router: Router,
    ) {
    }

    ngOnInit() {
        
        this.farm = this.route.snapshot.data.farmMaster;
        this.farm.DocId = this.route.snapshot.data.farmMaster.DocId;
        this.state$ = this.route.paramMap.pipe(
            map(() => window.history.state)
        );
     
    
        this.router.events
            .pipe(filter((evt: any) => evt instanceof RoutesRecognized), pairwise())
            .subscribe((events: RoutesRecognized[]) => {
      
                this.previousUrl = events[0].urlAfterRedirects;
                console.log('previous url', this.previousUrl);
    })
    
}

    refreshFarm(DocId: string) {
        console.log('Reload Farm :' + DocId)
        this.farmService.farmMaster(DocId).subscribe((response) => {
            this.farm.Record = response.Record;
            this.farm.DocId = response.DocId
            console.log(response);
        })

    }

    goBack() {
        // this.location.back();

        // TODO: Fix the back button to show highlight on previous selection

        console.log('Will Route back to : ' + this.previousUrl)
        
        this.state$
            .pipe(
                takeWhile(_ => this.alive),
            )
            .subscribe(state => {
                this.router.navigateByUrl(this.previousUrl, {state});
            });
    }