从下面的代码中，我有一个面板出现在for循环中，我想默认打开第一个索引paenl，我在下面发布我的实现，

<div *ngFor="let facility of slots; let i = index" class="facility-box">
        <div class="facility">
            <div >
                <button igxButton="outlined" class="btn" (click)="onClickViewSlots(slotExpPanel, facility)">
                    VIEW TIMES ({{facility?.slots[0].times.length}}) 
                </button>
            </div>
        </div>
        <div>
            <igx-expansion-panel #slotExpPanel>
                <igx-expansion-panel-body>
                    <div>
                           <div class="date date-appointment" *ngIf="facility?.slots[0]?.times.length > 0">
                                {{facility?.slots[0].date | date: 'EEE, MMM dd'}} :
                            </div>
                    </div>
                </igx-expansion-panel-body>
            </igx-expansion-panel>
        </div>
    </div>

组件：

`export class TestPanel implements OnInit {

   @ViewChild('slotExpPanel', { read: IgxExpansionPanelComponent, static: true })
   public slotExpPanel!: IgxExpansionPanelComponent;

   constructor() {
      this.slotExpPanel.open();

   }
 }

”
错误：

Cannot find open() of undefined

有人可以建议我在这里帮助。谢谢
我试图在for循环中打开第一个索引面板