diff --git a/src/stores/dialog.js b/src/stores/dialog.js
index 87023ef..5a95339 100644
--- a/src/stores/dialog.js
+++ b/src/stores/dialog.js
@@ -138,11 +138,15 @@ export const useDialogStore = defineStore('dialog', () => {
 
   function highlight(comment) {
     const target = document.querySelector('#comment-' + comment.id);
-    target.classList.add('highlight');
+    if (target) {
+      target.classList.add('highlight');
+    }
   }
   function unhighlight(comment) {
     const target = document.querySelector('#comment-' + comment.id);
-    target.classList.remove('highlight');
+    if (target) {
+      target.classList.remove('highlight');
+    }
   }
 
   return {