Type 'Observable<Response | Observable<Response>>' is not assignable to type 'Observable<Response>'

I have a simple service with the following content:

import { Injectable } from '@angular/core';
import { Http, Response } from '@angular/http';

import 'rxjs/add/observable/throw';
import 'rxjs/add/operator/catch';
import 'rxjs/add/operator/map';
import { Observable } from 'rxjs/Observable';

@Injectable()
export class AddressService {

  constructor(private http: Http) { }

  getAnything = (): Observable<Response> => {
    return this.http.get('https://my_api.com')
      .map(this.handleSuccess)
      .catch(this.handleError);
  }

  handleError = (error: Response): Observable<Response> => {
    return Observable.throw(error || 'Server Error');
  }

  handleSuccess = (response: Response): Observable<Response> => {
    let body;

    if (response.text()) {
      body = response.json();
    }

    return body || {};
  }
}

It was working perfectly, until I upgrade Typescript from 2.3.4 to 2.4.1.

Now, after upgrade, I'm getting the weird error:

Type 'Observable<Response | Observable<Response>>' is not assignable to type 'Observable<Response>'

What's the point here? What are the changes in TS 2.4.x that make my app stop working properly?