Add check for empty identifiers array

- add additional test data for this case

ee/app/assets/javascripts/security_dashboard/components/vulnerability_list.vue

@@ -211,6 +211,9 @@ export default {
         return acc;
       }, {});
     },
+    shouldShowExtraIdentifierCount(identifiers) {
+      return identifiers?.length > 1;
+    },
     shouldShowVulnerabilityPath(item) {
       return Boolean(item.location.image || item.location.file);
     },
@@ -338,7 +341,7 @@ export default {
           {{ primaryIdentifier(item.identifiers) }}
         </div>
         <div
-          v-if="extraIdentifierCount(item.identifiers)"
+          v-if="shouldShowExtraIdentifierCount(item.identifiers)"
           data-testid="vulnerability-more-identifiers"
           class="gl-text-gray-500"
         >

ee/spec/frontend/security_dashboard/components/mock_data.js

@@ -51,6 +51,7 @@ export const generateVulnerabilities = () => [
   },
   {
     id: 'id_2',
+    identifiers: [],
     title: 'Vulnerability 2',
     severity: 'high',
     state: 'opened',