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.
This module allows advertising a machine-readable document were outages,
planned or otherwise, may be reported.
See [XEP-0455: Service Outage Status] for further details, including
the format of the outage status document.
```lua
modules_enabled = {
-- other modules
"service_outage_status",
}
outage_status_urls = {
"https://uptime.example.net/status.json",
}
```
The outage status document should be hosted on a separate server to
ensure availability even if the XMPP server is unreachable.