Fix

src/app/services/navigation.service.spec.ts

@@ -0,0 +1,16 @@
+import { TestBed } from '@angular/core/testing';
+
+import { NavigationService } from './navigation.service';
+
+describe('NavigationService', () => {
+  let service: NavigationService;
+
+  beforeEach(() => {
+    TestBed.configureTestingModule({});
+    service = TestBed.inject(NavigationService);
+  });
+
+  it('should be created', () => {
+    expect(service).toBeTruthy();
+  });
+});

src/app/services/navigation.service.ts

@@ -0,0 +1,26 @@
+import { Injectable } from '@angular/core'
+import { Location } from '@angular/common'
+import { Router, NavigationEnd } from '@angular/router'
+
+@Injectable({ providedIn: 'root' })
+export class NavigationService {
+  private history: string[] = []
+
+  constructor(private router: Router, private location: Location) {
+    this.router.events.subscribe((event) => {
+      if (event instanceof NavigationEnd) {
+        this.history.push(event.urlAfterRedirects)
+      }
+    })
+  }
+
+  back(): void {
+    this.history.pop()
+    if (this.history.length > 0) {
+      this.location.back()
+    } else {
+      this.router.navigateByUrl('/')
+    }
+  }
+}
+