mod_http_muc_log: Fix exception on lack of trailing slash in room path A request to /room leads to the match call returning nil which in turn calls nodeprep(nil). In Prosody 0.11.x this does nothing and simply returns the nil, while in 0.12 it is an error. Now it redirects to the calendar view at /room/ - even for non-existant rooms. Discovered at a deployment with http_paths = { muc_log = "/" } and requests to /robots.txt and similar, which now result in a uses redirect before returning 404.

# Introduction

This module sends a [version query][xep0092] to clients when they
connect, and logs the response, allowing statistics of client usage to
be recorded.

Note that since this is per connection, there will be a bias towards
mobile clients on bad connections.

## Example

    info    Running Running Swift version 4.0