TODO $value->book 可能不存在

app/Http/Controllers/PaliTextController.php

@@ -203,6 +203,7 @@ class PaliTextController extends Controller
             if($request->get('view') !== 'book-toc'){
                 foreach ($chapters as $key => $value) {
                     if(is_object($value)){
+                        //TODO $value->book 可能不存在
                         $progress_key="/chapter_dynamic/{$value->book}/{$value->paragraph}/global";
                         $chapters[$key]->progress_line = Cache::get($progress_key);
                     }