I hope you are not referring to things like errno? Because it, just like a returned error, must be checked after every call that might set it, before you know if you can safely proceed with the next.
Otherwise, what happens when you keep calling functions and there already is an error present? Are all functions implemented with if(errno) return null guards at the top? That's putting a lot of trust into global state and library writers. How do you know which functions become noops and which continue working in state of error?
Additionally, that would be a debugging nightmare, because if you keep calling functions before examining the error, how do you know which call introduced the error first?
Otherwise, what happens when you keep calling functions and there already is an error present? Are all functions implemented with if(errno) return null guards at the top? That's putting a lot of trust into global state and library writers. How do you know which functions become noops and which continue working in state of error?
Additionally, that would be a debugging nightmare, because if you keep calling functions before examining the error, how do you know which call introduced the error first?