ng select in ANGLAR5问题:错误类型错误:对象(…)不是NgDropdownPanelComponent上的函数。ngOnInit(ng-select.js

我正在我的项目angular5中使用ng select 2.0.0,如 this link ,我可以从api rest spring引导中获得结果,但我遇到了一个问题,我在单击ng select时出现了此错误:

ERROR TypeError: Object(...) is not a function
at NgDropdownPanelComponent.ngOnInit (ng-select.js:1450)
at checkAndUpdateDirectiveInline (core.js:12352)
at checkAndUpdateNodeInline (core.js:13876)

而且我也不能选择我想要的信息(在本例中是属性‘nom’),这就像ng select被阻止了一样。

这是我的项目代码。组成部分html

<ng-select  *ngIf="_listClients"
             [items]="listClient"
              bindLabel ="nom"
              bindValue ="id"
            [(ngModel)]="selectedPersonId">

</ng-select>

<p>
  Selected city ID: {{selectedPersonId | json}}
</p>

这是文件项目。组成部分ts

    import {Component, OnInit, ViewChild} from '@angular/core';
import {ActivatedRoute, Router} from '@angular/router';
import {ProjetService} from '../../../../../service/projet.service';
import {Projet} from '../../Models/Projet';
import { ModalDirective } from 'ngx-bootstrap/modal';
import 'rxjs/add/operator/map';
import {ClientService} from '../../../../../service/client.service';

@Component({
  selector: 'app-projects',
  templateUrl: './projects.component.html',
  styleUrls: ['./projects.component.scss']
})
export class ProjectsComponent implements OnInit {

  selectedPersonId:number = null;
  _listClients :any;


constructor(private router:Router,
              private projetSevice:ProjetService,
              private clientServ:ClientService,
              private route: ActivatedRoute) { }

ngOnInit() {

       this.clientList();
  }


get listClient() {
     return this._listClients ? this._listClients.map(item => {
      return {id: item.id, prenom : item.prenom , nom : item.nom}
    }) : [];
  }


  clientList(){

     this.clientServ.getListClients()
       .subscribe((data:any)=>{
        this._listClients=data;
       },err=>{
         console.log('this is error ');
       })

  }

}

有什么帮助吗?