Restructure the frontend code to be more readable.

- Respond with a list of FileLinks instead of void in FileLinksResourceService#updateCollectionsForWorkPackage
- Move error handling up to the caller of FileLinksResourceService#updateCollectionsForWorkPackage
- Avoid nested subscribe calls

frontend/src/app/core/state/file-links/file-links.service.ts

@@ -31,12 +31,10 @@ import { Injectable } from '@angular/core';
 import { HttpHeaders } from '@angular/common/http';
 import { from, Observable } from 'rxjs';
 import {
-  catchError,
   groupBy,
   mergeMap,
   reduce,
   switchMap,
-  map,
   tap,
 } from 'rxjs/operators';
 
@@ -55,7 +53,7 @@ import idFromLink from 'core-app/features/hal/helpers/id-from-link';
 export class FileLinksResourceService extends ResourceCollectionService<IFileLink> {
   @InjectField() toastService:ToastService;
 
-  updateCollectionsForWorkPackage(fileLinksSelfLink:string):Observable<void> {
+  updateCollectionsForWorkPackage(fileLinksSelfLink:string):Observable<IFileLink[]> {
     return this.http
       .get<IHALCollection<IFileLink>>(fileLinksSelfLink)
       .pipe(
@@ -72,14 +70,14 @@ export class FileLinksResourceService extends ResourceCollectionService<IFileLin
             return acc;
           }, seed));
         }),
-        map((fileLinkCollections) => {
+        tap((fileLinkCollections) => {
           const storageId = idFromLink(fileLinkCollections.storage);
           const collectionKey = `${fileLinksSelfLink}?filters=[{"storage":{"operator":"=","values":["${storageId}"]}}]`;
           const collection = { _embedded: { elements: fileLinkCollections.fileLinks } } as IHALCollection<IFileLink>;
           insertCollectionIntoState(this.store, collection, collectionKey);
         }),
-        catchError(this.toastAndThrow.bind(this)),
-      ) as Observable<void>;
+        reduce((acc, group) => acc.concat(group.fileLinks), [] as IFileLink[]),
+      );
   }
 
   protected createStore():CollectionStore<IFileLink> {

frontend/src/app/features/work-packages/routing/wp-view-base/work-package-single-view.base.ts

@@ -45,6 +45,9 @@ import {
 import {
   WorkPackageNotificationService,
 } from 'core-app/features/work-packages/services/notifications/work-package-notification.service';
+import {
+  switchMap,
+} from 'rxjs/operators';
 import { InjectField } from 'core-app/shared/helpers/angular/inject-field.decorator';
 import { UntilDestroyedMixin } from 'core-app/shared/helpers/angular/until-destroyed.mixin';
 import { ApiV3Service } from 'core-app/core/apiv3/api-v3.service';
@@ -194,16 +197,19 @@ export class WorkPackageSingleViewBase extends UntilDestroyedMixin {
     if (this.workPackage.$links.fileLinks) {
       this.fileLinkResourceService
         .updateCollectionsForWorkPackage(this.workPackage.$links.fileLinks.href as string)
+        .pipe(
+          this.untilDestroyed(),
+          switchMap(() => this.projectsResourceService.lookup((this.workPackage.project as unknown&{ id:string }).id)),
+        )
         .subscribe(
-          () => {
-            this.projectsResourceService
-              .lookup((this.workPackage.project as unknown&{ id:string }).id)
-              .pipe(this.untilDestroyed())
-              .subscribe((project) => {
-                if (project._links.storages) {
-                  this.storages.updateCollection(project._links.self.href, project._links.storages);
-                }
-              });
+          (project) => {
+            if (project._links.storages) {
+              this.storages.updateCollection(project._links.self.href, project._links.storages);
+            }
+          },
+          (error) => {
+            this.toastService.addError(error);
+            throw error;
           },
         );
     }