--- a/util/pubsub.lua	Sat Aug 18 15:10:41 2018 +0100
+++ b/util/pubsub.lua	Sat Aug 18 15:26:35 2018 +0100
@@ -509,7 +509,7 @@
 		return false, "precondition-not-met";
 	end
 	if not self.config.itemcheck(item) then
-		return nil, "internal-server-error";
+		return nil, "invalid-item";
 	end
 	local node_data = self.data[node];
 	local ok = node_data:set(id, item);