Set `noteable_type` to use in notesApp

app/views/projects/issues/_discussion.html.haml

@@ -8,4 +8,5 @@
 %section.js-vue-notes-event
   #js-vue-notes{ data: { notes_data: notes_data(@issue),
     noteable_data: serialize_issuable(@issue),
+    noteable_type: 'issue',
     current_user_data: UserSerializer.new.represent(current_user, only_path: true).to_json } }

app/views/projects/merge_requests/show.html.haml

@@ -80,6 +80,7 @@
               - if has_vue_discussions_cookie?
                 #js-vue-mr-discussions{ data: { notes_data: notes_data(@merge_request),
                   noteable_data: serialize_issuable(@merge_request),
+                  noteable_type: 'merge_request',
                   current_user_data: UserSerializer.new.represent(current_user).to_json} }
 
       #commits.commits.tab-pane