删除开放图层中的特征

Question

我是Angular和Openlayers的新手（3）。所以基本上我想做的是使用存储在数组中的对象显示路由。但是问题出在我从数组中删除对象之后，它会触发错误

  

ERROR TypeError：无法读取未定义的属性'forEach'

如果我在aol功能之外单独显示对象，则没有错误，因此我确定在openlayers中所做的操作有问题。

this.xx = this.broadCastService.events.subscribe((ev) =>{
                this.configService.getConfig3(ev[0],ev[1]).subscribe((e: LineVariantTrack) =>{
                 if(ev[2]==true){
                  this.line.push(e);
                  console.log(this.line);
                 }
                 else{ 
                  this.line.splice(this.line.findIndex(el =>                                   el.lineVariantNumber==e.lineVariantNumber),1);       
                  console.log(this.line);
  
                }
              });
              });

  <div *ngFor="let l of  line">
 ERROR HERE<aol-feature *ngFor="let s of  l?.segments ;let i=index" [id]="i">
          <aol-geometry-linestring>
          <aol-collection-coordinates [coordinates]="[[s?.from?.position?.longitude || s?.to?.position?.longitude, s?.from?.position?.latitude || s?.to?.position?.latitude],[s?.to?.position?.longitude || s?.from?.position?.longitude, s?.to?.position?.latitude || s?.from?.position?.latitude]]"
              [srid]="'EPSG:4326'">
            </aol-collection-coordinates>
          </aol-geometry-linestring>
          <aol-style>
            <aol-style-stroke [width]="5" [color]="'blue'"></aol-style-stroke>
          </aol-style>
        </aol-feature>
      </div>