Merge pull request DSpace#6007 from tinsch/fix-duplicates-section-undefined-error

fix undefined error when duplicates section is not present for workspace item

Author: tdonohue

src/app/submission/objects/submission-objects.effects.ts

@@ -111,7 +111,8 @@ export class SubmissionObjectEffects {
 
         // Duplicates will ignore mandatory and display only when "always display" is set or there is data to show
         if (sectionDefinition.sectionType === SectionsType.Duplicates) {
-          enabled = (alwaysDisplayDuplicates() || isNotEmpty((action.payload.sections[sectionId] as WorkspaceitemSectionDuplicatesObject).potentialDuplicates));
+          const duplicatesSection = action.payload.sections?.[sectionId] as WorkspaceitemSectionDuplicatesObject | undefined;
+          enabled = (alwaysDisplayDuplicates() || isNotEmpty(duplicatesSection?.potentialDuplicates));
         }
 
         let sectionData;