Fatal error: Uncaught Error: Class 'Illuminate\Database\Eloquent\Relations\Relation' not found in /home/edmedu/www/edmeducation.co.kr/tw-dev/vendor/laravel/framework/src/Illuminate/Database/Eloquent/Relations/BelongsToMany.php:11 Stack trace: #0 {main} thrown in /home/edmedu/www/edmeducation.co.kr/tw-dev/vendor/laravel/framework/src/Illuminate/Database/Eloquent/Relations/BelongsToMany.php on line 11