Fatal error: Uncaught TypeError: mysqli_num_rows(): Argument #1 ($result) must be of type mysqli_result, bool given in C:\web\WSM\travered2019\dev\include\library.php:304 Stack trace: #0 C:\web\WSM\travered2019\dev\include\library.php(304): mysqli_num_rows() #1 C:\web\WSM\travered2019\dev\include\engine.php(84): changeCartSession() #2 C:\web\WSM\travered2019\dev\urlmanager.php(3): include('...') #3 {main} thrown in C:\web\WSM\travered2019\dev\include\library.php on line 304