Fixed no new line showing as null in select input

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

@@ -90,7 +90,13 @@ export default {
         // ignore null values match lines
         if (left) acc.push(left);
         // if the line_codes are identically, return to avoid duplicates
-        if (left?.line_code === right?.line_code) return acc;
+        if (
+          left?.line_code === right?.line_code ||
+          left?.type === 'old-nonewline' ||
+          right?.type === 'new-nonewline'
+        ) {
+          return acc;
+        }
         if (right && right.type !== 'match') acc.push(right);
         return acc;
       };