core: Fix 32/8 bit confusion in pack index listing

src/libostree/ostree-core.c

@@ -767,6 +767,8 @@ GVariant *
 ostree_object_name_serialize (const char *checksum,
                               OstreeObjectType objtype)
 {
+  g_assert (objtype >= OSTREE_OBJECT_TYPE_FILE
+            && objtype <= OSTREE_OBJECT_TYPE_COMMIT);
   return g_variant_new ("(su)", checksum, (guint32)objtype);
 }