[Port dspace-7_x] Catch and handle unsuccessful "convert rels to items" responses

src/app/item-page/simple/item-types/shared/item-relationships-utils.ts

@@ -5,8 +5,7 @@
 import { Relationship } from '../../../../core/shared/item-relationships/relationship.model';
 import { Item } from '../../../../core/shared/item.model';
 import {
-  getFirstSucceededRemoteDataPayload,
-  getFirstSucceededRemoteData
+  getFirstCompletedRemoteData
 } from '../../../../core/shared/operators';
 import { hasValue } from '../../../../shared/empty.util';
 import { InjectionToken } from '@angular/core';
@@ -77,24 +76,42 @@
  * @param {string} thisId       The item's id of which the relations belong to
  * @returns {(source: Observable<Relationship[]>) => Observable<Item[]>}
  */
-export const paginatedRelationsToItems = (thisId: string) =>
-  (source: Observable<RemoteData<PaginatedList<Relationship>>>): Observable<RemoteData<PaginatedList<Item>>> =>
+export const paginatedRelationsToItems = (thisId: string) => (source: Observable<RemoteData<PaginatedList<Relationship>>>): Observable<RemoteData<PaginatedList<Item>>> =>
     source.pipe(
-      getFirstSucceededRemoteData(),
+      getFirstCompletedRemoteData(),
       switchMap((relationshipsRD: RemoteData<PaginatedList<Relationship>>) => {
         return observableCombineLatest(
           relationshipsRD.payload.page.map((rel: Relationship) =>
             observableCombineLatest([
-              rel.leftItem.pipe(getFirstSucceededRemoteDataPayload()),
-              rel.rightItem.pipe(getFirstSucceededRemoteDataPayload())]
+              rel.leftItem.pipe(
+                getFirstCompletedRemoteData(),
+                map((rd: RemoteData<Item>) => {
+                  if (rd.hasSucceeded) {
+                    return rd.payload;
+                  } else {
+                    return null;
+                  }
+                })
+              ),
+              rel.rightItem.pipe(
+                getFirstCompletedRemoteData(),
+                map((rd: RemoteData<Item>) => {
+                  if (rd.hasSucceeded) {
+                    return rd.payload;
+                  } else {
+                    return null;
+                  }
+                })
+              ),
+              ]
             )
-          )).pipe(
+          )
+        ).pipe(
           map((arr) =>
-            arr
-              .map(([leftItem, rightItem]) => {
-                if (leftItem.id === thisId) {
+            arr.map(([leftItem, rightItem]) => {
+                if (hasValue(leftItem) && leftItem.id === thisId) {
                   return rightItem;
-                } else if (rightItem.id === thisId) {
+                } else if (hasValue(rightItem) && rightItem.id === thisId) {
                   return leftItem;
                 }
               })