618: Type System Says No

6735.732 - 6756.519 John Siracusa

Error checking is the most important part of the programming! I've omitted error checking. Are you freaking kidding me? All I want to know is where can this go wrong? What do I have to check for and where? So I tell that the transaction is valid. Do I have to do it? Do I not have to do it? What are the possible error scenarios? Where do I, like I've omitted error checking for brevity.