bugfix: filter sometimes render buggy hierarchy guiding dashed lnies

src/components/flatTree/clustering.pipe.ts

+import { Pipe, PipeTransform } from "@angular/core";
+
+@Pipe({
+  name : 'clusteringPipe'
+})
+
+export class ClusteringPipe implements PipeTransform{
+  public transform(arr:any[],num:number = 100):any[][]{
+    return arr.reduce((acc,curr,idx,arr) => idx % num === 0 
+      ? acc.concat([arr.slice(idx, idx + num)])
+      : acc ,[])
+  }
+}
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