Merge branch 'slashmanov/fix-adding-discussions-to-rebased-mrs' into 'master'

Add a safeguard against non-matching diff discussion positions

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/144865



Merged-by: Phil Hughes <me@iamphill.com>
Approved-by: Phil Hughes <me@iamphill.com>
Co-authored-by: Stanislav Lashmanov <slashmanov@gitlab.com>

app/assets/javascripts/diffs/store/mutations.js

@@ -210,6 +210,8 @@ export default {
 
     if (diffLines.length && positionType !== FILE_DIFF_POSITION_TYPE) {
       const line = diffLines.find(isTargetLine);
+      // skip if none of the discussion positions matched a diff position
+      if (!line) return;
       const discussions = addDiscussion(line.discussions || []);
       Object.assign(line, {
         discussions,