anchor.diff:    (unless (shovel-vm-prim0:is-bool (car (vm-stack vm)))
       (raise-shovel-error vm "Argument must be a boolean.")))
   
  +(declaim (inline check-vm-without-error))
   (defun check-vm-without-error (vm)
     (declare (optimize speed (safety 0))
              (type vm vm))
  
positive.code:   (alexandria:when-let (err (vm-programming-error vm))
      (error err)))
  
  (defun check-cells-quota (vm)
    (declare (optimize speed (safety 0))
             (type vm vm))
  
negative.code:                          :num-args (second args))
            (vm-stack vm))
      ;; for the pushed callable (5 fields)
      (increment-cells-quota vm 5)
      (inc-pc vm)))
  
  (defun handle-new-frame (vm instruction)
  