fix an issue where an empty bitstream page would cause an error

src/app/core/data/base-response-parsing.service.ts

@@ -14,7 +14,7 @@ function isObjectLevel(halObj: any) {
 }
 
 function isPaginatedResponse(halObj: any) {
-  return hasValue(halObj.page) && hasValue(halObj._embedded);
+  return hasValue(halObj.page);
 }
 
 /* tslint:disable:max-classes-per-file */
@@ -77,7 +77,9 @@ export abstract class BaseResponseParsingService {
     let list = data._embedded;
 
     // Workaround for inconsistency in rest response. Issue: https://github.com/DSpace/dspace-angular/issues/238
-    if (!Array.isArray(list)) {
+    if (hasNoValue(list)) {
+      list = [];
+    } else if (!Array.isArray(list)) {
       list = this.flattenSingleKeyObject(list);
     }
     const page: ObjectDomain[] = this.processArray(list, requestHref);