[Multiple issue assignees] Fix MR show[ci skip]

app/views/shared/issuable/form/_merge_request_assignee.html.haml

@@ -28,4 +28,4 @@
 
   .selectbox.hide-collapsed
     = f.hidden_field 'assignee_id', value: merge_request.assignee_id, id: 'issue_assignee_id'
-    = dropdown_tag('Select assignee', options: { toggle_class: 'js-user-search js-author-search', title: 'Assign to', filter: true, dropdown_class: 'dropdown-menu-user dropdown-menu-selectable dropdown-menu-author', placeholder: 'Search users', data: { first_user: (current_user.username if current_user), current_user: true, project_id: (@project.id if @project), author_id: merge_request.author_id, field_name: "#{merge_request.to_ability_name}[assignee_id]", issue_update: merge_request_json_path(merge_request), ability_name: 'merge_request', null_user: true } })
+    = dropdown_tag('Select assignee', options: { toggle_class: 'js-user-search js-author-search', title: 'Assign to', filter: true, dropdown_class: 'dropdown-menu-user dropdown-menu-selectable dropdown-menu-author', placeholder: 'Search users', data: { first_user: (current_user.username if current_user), current_user: true, project_id: @project&.id, author_id: merge_request.author_id, field_name: 'merge_request[assignee_id]', issue_update: issuable_json_path(merge_request), ability_name: 'merge_request', null_user: true } })