Merge branch 'fix-mr-comment-commit-pruned' into 'master'

Gracefully handle notes on deleted commits in merge requests

Closes #3250

See merge request !3402
Signed-off-by: Rémy Coutable <remy@rymai.me>

CHANGELOG

@@ -21,6 +21,7 @@ v 8.6.2
   - Fix background when editing a highlighted note. !3423
   - Remove tabstop from the WIP toggle links. !3426
   - Ensure private project snippets are not viewable by unauthorized people.
+  - Gracefully handle notes on deleted commits in merge requests (Stan Hu). !3402
 
 v 8.6.1
   - Add option to reload the schema before restoring a database backup. !2807

app/helpers/notes_helper.rb

@@ -5,9 +5,11 @@ module NotesHelper
   end
 
   def note_target_fields(note)
+    if note.noteable
       hidden_field_tag(:target_type, note.noteable.class.name.underscore) +
         hidden_field_tag(:target_id, note.noteable.id)
     end
+  end
 
   def note_editable?(note)
     note.editable? && can?(current_user, :admin_note, note)

app/views/projects/notes/discussions/_commit.html.haml

 - note = discussion_notes.first
+- commit = note.noteable
+- commit_description = commit ? 'commit' : 'a deleted commit'
 .discussion.js-toggle-container{ class: note.discussion_id }
   .discussion-header
     .discussion-actions
@@ -7,8 +9,9 @@
         Show/hide discussion
     %div
       = link_to_member(@project, note.author, avatar: false)
-      started a discussion on commit
-      = link_to(note.noteable.short_id, namespace_project_commit_path(note.project.namespace, note.project, note.noteable), class: 'monospace')
+      %p started a discussion on #{commit_description}
+      - if commit
+        = link_to(commit.short_id, namespace_project_commit_path(note.project.namespace, note.project, note.noteable), class: 'monospace')
     .last-update.hide.js-toggle-content
       - last_note = discussion_notes.last
       last updated by