Opencart 500 server error

Question

I am getting such an error at image below while OpenCart complete the pay option. How could this be solved? hi when I want to click Continue button to continue the order after i finish my payment method then it goes to Checkout Confirmation" The continue button to checkout confirmation does not function it freeze like no action to take. but i look in code. i go to some javascript code. to continue it i try to trace which action it will take i think this javascript

They have the same problem with me. They have solved the problem here, but I do not know how they do it Opencart Fatal error: Opencart Fatal error: Call to a member function get() on a non-object