+(defun type-from-number (type-number &optional error)
+ (multiple-value-bind (type found)
+ (gethash type-number *number-to-type-hash*)
+ (when (and error (not found))
+ (let ((name (find-type-name type-number)))
+ (if name
+ (error "Type number not registered: ~A (~A)" type-number name)
+ (error "Invalid type number: ~A" type-number))))
+ type))