mod_roster_command: Fix subscription when the "user JID" is a bare domain. Do not attempt to update the roster when the user is bare domain (e.g. a component), since they don't have rosters and the attempt results in an error: $ prosodyctl mod_roster_command subscribe proxy.example.com contact@example.com xxxxxxxxxxFailed to execute command: Error: /usr/lib/prosody/core/rostermanager.lua:104: attempt to concatenate local 'username' (a nil value) stack traceback: /usr/lib/prosody/core/rostermanager.lua:104: in function 'load_roster' /usr/lib/prosody/core/rostermanager.lua:305: in function 'set_contact_pending_out' mod_roster_command.lua:44: in function 'subscribe'

# Introduction

This module implements [XEP-xxxx: Room Activity Indicators](https://xmpp.org/extensions/inbox/room-activity-indicators.html).

## Requirements

This module currently depends on mod_muc_markers, so review the requirements for that module.

# Configuring

## Enabling

``` {.lua}
Component "rooms.example.net" "muc"
modules_enabled = {
    "muc_rai";
    "muc_markers";
    "muc_mam";
}
```

## Settings

|Name |Description |Default |
|-----|------------|--------|
|muc_rai_max_subscribers| Maximum number of active subscriptions allowed | 1024 |

# Compatibility

Requires Prosody trunk (2020-04-15+).