--- a/core/sessionmanager.lua	Sat Nov 02 13:09:54 2019 +0100
+++ b/core/sessionmanager.lua	Sat Nov 02 13:24:33 2019 +0100
@@ -150,7 +150,7 @@
 		resource = event_payload.resource;
 	end
 
-	resource = resourceprep(resource);
+	resource = resourceprep(resource or "");
 	resource = resource ~= "" and resource or generate_identifier();
 	--FIXME: Randomly-generated resources must be unique per-user, and never conflict with existing