UFAL/Do not add dtoken into the URL if it is null (#860)

Author: milanmajchrak

src/app/bitstream-page/clarin-zip-download-page/clarin-zip-download-page.component.ts

@@ -71,8 +71,11 @@ export class ClarinZipDownloadPageComponent extends ClarinBitstreamDownloadPageC
           this.bitstreams$.next([...current, ...bitstreamsRD.payload.page]);
           this.bitstreamRD$ = createSuccessfulRemoteDataObject$(this.bitstreams$.getValue()[0]);
           this.dtoken = isUndefined(this.route.snapshot.queryParams.dtoken) ? null : this.route.snapshot.queryParams.dtoken;
-          this.zipDownloadLink.next(this.halService.getRootHref() +
-            `/core/items/${itemRD.payload.uuid}/allzip?handleId=${itemRD?.payload?.handle}&dtoken=${this.dtoken}`);
+          const baseUrl = this.halService.getRootHref() +
+            `/core/items/${itemRD.payload.uuid}/allzip?handleId=${itemRD?.payload?.handle}`;
+          // Do not add `dtoken` into the URL if it is null
+          const dtokenParam = this.dtoken ? `&dtoken=${this.dtoken}` : '';
+          this.zipDownloadLink.next(baseUrl + dtokenParam);
           super.ngOnInit();
         }
       });