mod_invites_register: Fix missing 'from' attribute (thanks Martin)
This should probably cause a noisier error in Prosody, than the current
> No hosts[from_host] (please report): <stanza>
A stack trace would have been useful, for example.
This module implements the [Server
Optimization](https://xmpp.org/extensions/xep-0410.html#serveroptimization)
part of [XEP-0410: MUC Self-Ping]
# Usage
The module is loaded on MUC components:
```lua
Component "muc.example.com" "muc"
modules_enabled = {
"muc_ping";
}
```
# Configuration
No options.
# Compatibility
It should work with Prosody up until 0.10.x.
Prosody 0.11.x and trunk natively supports XEP-0410 so this module is **not** needed.