fix: protect null category

Author: joanagmaia

frontend/src/modules/admin/modules/collections/components/lf-collection-table.vue

@@ -29,10 +29,10 @@
 
         <lf-table-cell class="pl-3">
           <p class="text-medium mb-0.5">
-            {{ collection.category.name }}
+            {{ collection.category?.name }}
           </p>
           <p class="text-tiny text-gray-500">
-            {{ collection.category.categoryGroupName }} ({{ collection.category.categoryGroupType === 'vertical' ? 'Industry' : 'Stack' }})
+            {{ collection.category?.categoryGroupName }} ({{ collection.category?.categoryGroupType === 'vertical' ? 'Industry' : 'Stack' }})
           </p>
         </lf-table-cell>