#286: Restore CommentThreads nextPageToken

Solving [the Stack Overflow question 78877647](https://stackoverflow.com/q/78877647).

commentThreads.php

@@ -155,7 +155,8 @@ function getAPI($videoId, $commentId, $order, $continuationToken, $simulatedCont
         ];
         $answerItems[$properties['toolbarStateKey']] = $answerItem;
     }
-    foreach ($result['onResponseReceivedEndpoints'][1]['reloadContinuationItemsCommand']['continuationItems'] as $item) {
+    $continuationItems = $result['onResponseReceivedEndpoints'][1]['reloadContinuationItemsCommand']['continuationItems'];
+    foreach ($continuationItems as $item) {
         $commentThreadRenderer = $item['commentThreadRenderer'];
         $toolbarStateKey = $commentThreadRenderer['commentViewModel']['commentViewModel']['toolbarStateKey'];
         // How to avoid repeating path?
@@ -165,9 +166,12 @@ function getAPI($videoId, $commentId, $order, $continuationToken, $simulatedCont
         if (doesPathExist($commentThreadRenderer, 'commentViewModel/commentViewModel/pinnedText')) {
             $answerItems[$toolbarStateKey]['snippet']['topLevelComment']['snippet']['isPinned'] = true;
         }
-        $answerItems[$toolbarStateKey]['snippet']['topLevelComment']['snippet']['nextPageToken'] = $commentThreadRenderer['replies']['commentRepliesRenderer']['contents'][0]['continuationItemRenderer']['continuationEndpoint']['continuationCommand']['token'];
+        if ($toolbarStateKey !== null) {
+            $answerItems[$toolbarStateKey]['snippet']['topLevelComment']['snippet']['nextPageToken'] = $commentThreadRenderer['replies']['commentRepliesRenderer']['contents'][0]['continuationItemRenderer']['continuationEndpoint']['continuationCommand']['token'];
+        }
     }
     $answerItems = array_values($answerItems);
+    $nextContinuationToken = $continuationItems[20]['continuationItemRenderer']['continuationEndpoint']['continuationCommand']['token'];
 
     $answer = [
         'kind' => 'youtube#comment' . ($isTopLevelComment ? 'Thread' : '') . 'ListResponse',