MonoTypeOperatorFunction <...> не может быть назначен параметру типа OperatorFunction <..>

Question

Я использую Ionic 4.10.2 и пытаюсь получить службу аутентификации, написанную с использованием примера из учебника, который я нашел (https://www.techiediaries.com/ionic-jwt-authentication-httpclient/, за исключением того, что я использую java REST-сервер на сервере)

Я получаю ошибку:

[ng] ERROR in src/app/auth/auth.service.ts(40,17): error TS2345: Argument of type 'MonoTypeOperatorFunction<AuthResponse>' is not assignable to parameter of type 'OperatorFunction<HttpResponse<AuthResponse>, AuthResponse>'.
[ng]   Types of parameters 'source' and 'source' are incompatible.
[ng]     Type 'Observable<HttpResponse<AuthResponse>>' is not assignable to type 'Observable<AuthResponse>'.
[ng]       Type 'HttpResponse<AuthResponse>' is not assignable to type 'AuthResponse'.
[ng]         Property 'user' is missing in type 'HttpResponse<AuthResponse>'.
[ng] src/app/web-services/test-page/test-page.page.ts(4,40): error TS2307: Cannot find module './test-rest-service.servi
ce'.
[ng] src/app/web-services/test-rest-service.service.ts(42,30): error TS2304: Cannot find name 'apiUrl'.
[ng]

Все ответы, которые я нашел в Интернете, говорят, что это может быть связано с несколькими версиями rxjs в проекте.Но я вижу только одно:

    PS C:\projectFolder> npm list rxjs
    MobileAppTemplate@0.0.1 C:\projectFolder
    +-- @angular-devkit/architect@0.12.4
    | `-- rxjs@6.3.3  deduped
    +-- @angular-devkit/build-angular@0.12.4
    | +-- @angular-devkit/build-webpack@0.12.4
    | | `-- rxjs@6.3.3  deduped
    | +-- @ngtools/webpack@7.2.4
    | | `-- rxjs@6.3.3  deduped
    | `-- rxjs@6.3.3  deduped
    +-- @angular-devkit/core@7.2.4
    | `-- rxjs@6.3.3  deduped
    +-- @angular-devkit/schematics@7.2.4
    | `-- rxjs@6.3.3  deduped
    +-- @angular/cli@7.2.4
    | +-- @schematics/update@0.12.4
    | | `-- rxjs@6.3.3  deduped
    | `-- inquirer@6.2.1
    |   `-- rxjs@6.3.3  deduped
    `-- rxjs@6.3.3

Вот код:

import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { tap } from 'rxjs/operators';
import { Observable, BehaviorSubject } from 'rxjs';
import { Storage } from '@ionic/storage';

import { User } from './user';
import { AuthResponse } from './auth-response';

@Injectable({
  providedIn: 'root'
})
export class AuthService {

    AUTH_SERVER_ADDRESS: string = "http://SERVERIP:8080/WebServicesTemplate";
    REGISTRATION_URL: string = this.AUTH_SERVER_ADDRESS + "/user/register";
    LOGIN_URL: string = this.AUTH_SERVER_ADDRESS + "/login";
    ACCESS_TOKEN_NAME: string = "ACCESS_TOKEN";
    ACCESS_TOKEN_EXPIRATION_TIME: string = "EXPIRES_IN";
    authSubject = new BehaviorSubject(false);

    constructor(private httpClient: HttpClient, private storage: Storage) { }

    register(user: User): Observable<AuthResponse> {
        return this.httpClient.post<AuthResponse>(`${this.REGISTRATION_URL}`, user)
            .pipe(
                tap(async (response: AuthResponse) => {
                    if(response.user) {
                        await this.storage.set(this.ACCESS_TOKEN_NAME, response.user.accessToken);
                        await this.storage.set(this.ACCESS_TOKEN_EXPIRATION_TIME, response.user.expiresIn);
                        this.authSubject.next(true);
                    }
                })
            );
    }// end register(.)

    login(user: User): Observable<AuthResponse> {
        return this.httpClient.post<AuthResponse>(`${this.LOGIN_URL}`, user, {observe: "response"})
            .pipe(
                tap(async (response: AuthResponse ) => {
                    if(response.user) {
                        await this.storage.set(this.ACCESS_TOKEN_NAME, response.user.accessToken);
                        await this.storage.set(this.ACCESS_TOKEN_EXPIRATION_TIME, response.user.expiresIn);
                        this.authSubject.next(true);
                    }
                })
            );
    }// end login(.)

    async logout() {
        await this.storage.remove(this.ACCESS_TOKEN_NAME);
        await this.storage.remove(this.ACCESS_TOKEN_EXPIRATION_TIME);
        this.authSubject.next(false);
    }

    isLoggedIn() {
        return this.authSubject.asObservable();
    }
}

Что я могу сделать, чтобы решить эту проблему?