Merge branch...

Merge branch '28376-merge-request-comments-have-stopped-appearing-for-the-whole-project' into 'master'

Fix for invalid diff lines on corrupt diff notes

See merge request gitlab-org/gitlab!23786

app/models/concerns/discussion_on_diff.rb

@@ -40,7 +40,7 @@ module DiscussionOnDiff
   # Returns an array of at most 16 highlighted lines above a diff note
   def truncated_diff_lines(highlight: true, diff_limit: nil)
     return [] unless on_text?
-    return [] if diff_line.nil? && first_note.is_a?(LegacyDiffNote)
+    return [] if diff_line.nil?
 
     diff_limit = [diff_limit, NUMBER_OF_TRUNCATED_DIFF_LINES].compact.min
     lines = highlight ? highlighted_diff_lines : diff_lines

changelogs/unreleased/28376-merge-request-comments-have-stopped-appearing-for-the-whole-project.yml

+---
+title: Fix Merge Request comments when some notes are corrupt
+merge_request: 23786
+author:
+type: fixed

spec/models/concerns/discussion_on_diff_spec.rb

@@ -59,6 +59,18 @@ describe DiscussionOnDiff do
       end
     end
 
+    context "when the diff line does not exist on a corrupt diff note" do
+      subject { create(:diff_note_on_merge_request, line_number: 18).to_discussion }
+
+      before do
+        allow(subject).to receive(:diff_line) { nil }
+      end
+
+      it "returns an empty array" do
+        expect(truncated_lines).to eq([])
+      end
+    end
+
     context 'when the discussion is on an image' do
       subject { create(:image_diff_note_on_merge_request).to_discussion }