Warning: Trying to access array offset on null in C:\Websites\acco\public_html\contents\ajax_specsheet.php on line 29

Fatal error: Uncaught TypeError: array_merge(): Argument #2 must be of type array, null given in C:\Websites\acco\public_html\contents\ajax_specsheet.php:30 Stack trace: #0 C:\Websites\acco\public_html\contents\ajax_specsheet.php(30): array_merge() #1 C:\Websites\acco\public_html\pdf.php(10): include('...') #2 {main} thrown in C:\Websites\acco\public_html\contents\ajax_specsheet.php on line 30