--- a/mod_filter_chatstates/mod_filter_chatstates.lua	Mon Aug 25 00:38:14 2014 +0200
+++ b/mod_filter_chatstates/mod_filter_chatstates.lua	Mon Aug 25 12:03:52 2014 +0100
@@ -1,6 +1,9 @@
 local filters = require "util.filters";
 local st = require "util.stanza";
 
+local dummy_stanza_mt = setmetatable({ __tostring = function () return ""; end }, { __index = st.stanza_mt });
+local dummy_stanza = setmetatable(st.stanza(), dummy_stanza_mt);
+
 module:depends("csi");
 
 local function filter_chatstates(stanza)
@@ -8,11 +11,11 @@
 		stanza = st.clone(stanza);
 		stanza:maptags(function (tag)
 			if tag.attr.xmlns ~= "http://jabber.org/protocol/chatstates" then
-				return tag
+				return tag;
 			end
 		end);
 		if #stanza.tags == 0 then
-			return nil;
+			return dummy_stanza;
 		end
 	end
 	return stanza;