Fatal error: Uncaught Error: Class "PhpOffice\Math\Element\AbstractElement" not found in D:\Apache24\www\silian\back-end\vendor\phpoffice\math\src\Math\Element\Operator.php:5 Stack trace: #0 {main} thrown in D:\Apache24\www\silian\back-end\vendor\phpoffice\math\src\Math\Element\Operator.php on line 5