X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~mdw/git/clg/blobdiff_plain/1bf1bfc9dae1911ac64a7d1732e1912ec81700f4..e59b159786355b542f5036b1b40247666fe195f2:/glib/gobject.lisp

diff --git a/glib/gobject.lisp b/glib/gobject.lisp
index bfde9d1..68ee82c 100644
--- a/glib/gobject.lisp
+++ b/glib/gobject.lisp
@@ -586,6 +586,10 @@ (defun expand-gobject-type (type forward-p options &optional (metaclass 'gobject
   (let ((supers (cons (supertype type) (implements type)))
 	(class  (type-from-number type))
 	(slots (getf options :slots)))
+    (when (member nil supers)
+      (error "Got NIL as a supertype for ~A (full list: ~A).~%~
+              This shouldn't happen - is the parent type correctly registered?"
+             (find-foreign-type-name type) supers))
     `(defclass ,class ,supers
 	 ,(unless forward-p
 	    (slot-definitions class (query-object-class-properties type) slots))