From 0e25f8d43ea48d0a3db7b1b16f6c40f3077306ce Mon Sep 17 00:00:00 2001
From: Badlop <badlop@process-one.net>
Date: Mon, 23 May 2022 16:41:19 +0200
Subject: [PATCH] Fix mod_conversejs crash when mod_register not enabled
 (#3824)

---
 src/mod_conversejs.erl | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/src/mod_conversejs.erl b/src/mod_conversejs.erl
index 767a3824b..61cec2322 100644
--- a/src/mod_conversejs.erl
+++ b/src/mod_conversejs.erl
@@ -183,10 +183,19 @@ get_register_options(Server) ->
              (_) -> false
           end,
           ejabberd_auth:auth_modules(Server)),
-    Modules = mod_register_opt:allow_modules(Server),
+    Modules = get_register_modules(Server),
     ModRegisterAllowsMe = (Modules == all) orelse lists:member(?MODULE, Modules),
     [{<<"allow_registration">>, AuthSupportsRegister and ModRegisterAllowsMe}].
 
+get_register_modules(Server) ->
+    try mod_register_opt:allow_modules(Server)
+    catch
+        error:{module_not_loaded, mod_register, _} ->
+            ?DEBUG("mod_conversejs couldn't get mod_register configuration for "
+                   "vhost ~p: module not loaded in that vhost.", [Server]),
+            []
+    end.
+
 get_extra_options(Host) ->
     RawOpts = gen_mod:get_module_opt(Host, ?MODULE, conversejs_options),
     lists:map(fun({Name, <<"true">>}) -> {Name, true};