mod_sasl2_fast: Improve handling when SASL profile unexpectedly lacks CB
This fixes a traceback reported by riau, but likely does not solve the
underlying cause, whatever that is.
# Introduction
This module adds a room configuration option to hide inline media from
unaffiliated users in MUCs and display them as links instead.
This can be useful in public channels where content posted by users should not
be shown by default.
# Configuring
## Enabling
``` {.lua}
Component "rooms.example.net" "muc"
modules_enabled = {
"muc_restrict_media";
}
```
## Settings
A default setting can be provided in the config file:
``` {.lua}
muc_room_default_restrict_media = true
```