From cf40daf663f0c88ebb0e42356420fe614c7d3af4 Mon Sep 17 00:00:00 2001
From: Badlop <badlop@process-one.net>
Date: Sat, 4 Apr 2015 13:48:17 +0200
Subject: [PATCH] Replace undefined value with empty one
 (processone/ejabberd-contrib#92)

---
 src/ejabberd_xmlrpc.erl | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/ejabberd_xmlrpc.erl b/src/ejabberd_xmlrpc.erl
index b1bd164a6..904604fc9 100644
--- a/src/ejabberd_xmlrpc.erl
+++ b/src/ejabberd_xmlrpc.erl
@@ -444,6 +444,8 @@ format_arg(Arg, binary) when is_list(Arg) -> list_to_binary(Arg);
 format_arg(Arg, binary) when is_binary(Arg) -> Arg;
 format_arg(Arg, string) when is_list(Arg) -> Arg;
 format_arg(Arg, string) when is_binary(Arg) -> binary_to_list(Arg);
+format_arg(undefined, binary) -> <<>>;
+format_arg(undefined, string) -> "";
 format_arg(Arg, Format) ->
     ?ERROR_MSG("don't know how to format Arg ~p for format ~p", [Arg, Format]),
     throw({error_formatting_argument, Arg, Format}).