sfa error checking

[GZ at MIT-MC (Gail Zacharias)]

Consider the following session:
    (defun nothin N '())
    NOTHIN 
    (setq test (sfa-create (function nothin) 17. 'testing))
    #SFA-|TESTING|-70766 
    (open test)
    NIL 
    (close test)
    NIL 
    (deletef test)
    NIL 
    (filepos test 13.)
    NIL 
    (sfa-call test (function untyi) ())
    NIL 
    (tyo 3 test)
    T 
    (out test 2)
    NIL 
    (force-output test)
    NIL 
    (prin1 1 test)
    T 
    (princ 'a test)
    T 
    (print 'foo test)
    T 
    (cursorpos test)
    NIL 
    (in test)			;; Well, at least this one errs out
    ;NIL NON-FIXNUM VALUE
  
Do I have to define all these operations just to have them err out?
TYI is the only one that actually complains that it is not supported.