用angular2发布请愿书

Question

我尝试用angular2创建用户注册，但我不明白为什么会出问题。

启动angular2的错误是以下错误。

A function whose declared type is neither 'void' nor 'any' must return a value.

所以我有以下代码

在组件中

import { Component, OnInit } from '@angular/core';
import { User} from '../../usuarios/signup/user';
import { Router , ActivatedRoute } from '@angular/router';
import { SignUpService } from '../../usuarios/signup/signup.service';     
@Component({
  selector: 'app-form',
  templateUrl: './signup.component.html'
})    
export class SignUpComponent implements OnInit {

  usuario: User = new User()

  constructor(private signUpService:SignUpService,private router:Router , private activatedRoute:ActivatedRoute) {}

  ngOnInit() {
  }

  userRegistration(): void {
    this.signUpService.userRegistration(this.usuario);
  }

}

和服务

import { Injectable } from '@angular/core';
import { User } from '../../usuarios/signup/user';
import { HttpClient,HttpHeaders} from '@angular/common/http';
import {Observable} from 'rxjs/Observable';
import 'rxjs/add/operator/map';

    @Injectable({
      providedIn: 'root'
    })

    export class SignUpService {

        private urlEndpoint:string = 'http://localhost:8584/api/public/v1/countries';

        private httpHeaders = new HttpHeaders ({'Content-type':'application/json'});

        constructor(private http:HttpClient){}

        userRegistration(user:User){
          this.http.post(this.urlEndpoint,user,{headers:this.httpHeaders});
        }

    }

用户模型

现在，此请愿书正在与Postman合作。