Presumably you mean "user provided a string which was supposed to be decodable as an int, but was not"? If so, then yes, this should be handled as an input erro

Presumably you mean "user provided a string which was supposed to be decodable as an int, but was not"? If so, then yes, this should be handled as an input error and not as an exception (programmer error). I don't know if you meant this as a criticism of Go or not, but you should find that Go programs almost always return errors (as opposed to panicking) under such circumstances.