In_App_Purchase error

So, it’s been over two weeks since I created a Product on the Play Console, now, I go back to the app that I created, and instead of showing the purchase window, I get the following error: Runtime Error
Attempt to invoke virtual method
3.BillingProcessor.purchase(andr, java.lang.String)
on a null object reference

What shall I do?![Screenshot_20190423-201504

This means you are trying to do a True, False, And, Or, Xor operation on a variable that is empty or does not exist.

After you make a Product purchase you need to consume it.

Can you show the billing or get purchases blocks you are using.