error in c++

symfony check:requirements Fatal error: Using $this when not in object context in C:\Users\Admin\.symfony\cache\check.php on line 778 exit status 255

Uncaught Error: Call to a member function prepare() on null in C:\xampp\htdocs\facultate\CosCump\product.php:5 Stack trace: #0 {main} thrown in C:\xampp\htdocs\facultate\CosCump\product.php on line 5

[ERROR] InvalidArgumentException: Wrong file in C:\xampp\htdocs\magento2.4\lib\internal\Magento\Framework\Image\Adapter\Gd2.php:64 Stack trace

opencv(4.4.0) c:\users\appveyor\appdata\local\temp\1\pip-req-build-71670poj\opencv\modules\imgproc\src\color.cpp:182: error: (-215:assertion failed) !_src.empty() in function

51 13 c:\users\usuario\documents\destajo 1.cpp [error] 'gotoxy' was not declared in this scope