Fix for displaying left side comments when no discussion available

app/assets/javascripts/diffs/components/parallel_diff_comment_row.vue

@@ -57,7 +57,9 @@ export default {
       );
     },
     showRightSideCommentForm() {
-      return this.line.right.type && this.diffLineCommentForms[this.rightLineCode];
+      return (
+        this.line.right && this.line.right.type && this.diffLineCommentForms[this.rightLineCode]
+      );
     },
     className() {
       return (this.left && this.line.left.discussions.length > 0) ||

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

@@ -49,12 +49,14 @@ export const assignDiscussionsToDiff = ({ state }, allLineDiscussions) => {
           }
         }
 
-        const targetInlineLine = selectedFile.highlightedDiffLines.find(
-          line => line.lineCode === discussions[0].line_code,
-        );
+        if (selectedFile.highlightedDiffLines) {
+          const targetInlineLine = selectedFile.highlightedDiffLines.find(
+            line => line.lineCode === discussions[0].line_code,
+          );
 
-        if (targetInlineLine) {
-          Object.assign(targetInlineLine, { discussions });
+          if (targetInlineLine) {
+            Object.assign(targetInlineLine, { discussions });
+          }
         }
       }
     }