Lisp is allowed to signal an error at compile time, however in this case (too many arguments) the error is specified to be of type PROGRAM-ERROR, and SB-INT:BUG is not a subclass of PROGRAM-ERROR.
Lisp is allowed to signal an error at compile time, however in this case (too many arguments) the error is specified to be of type PROGRAM-ERROR, and SB-INT:BUG is not a subclass of PROGRAM-ERROR.