Fatal error: Uncaught Error: Class "Illuminate\Database\Eloquent\Relations\Relation" not found in /opt/lampp/htdocs/forum/flarum/vendor/illuminate/database/Eloquent/Relations/BelongsToMany.php:17 Stack trace: #0 {main} thrown in /opt/lampp/htdocs/forum/flarum/vendor/illuminate/database/Eloquent/Relations/BelongsToMany.php on line 17