This isn't an error report, more of a validation idea for creating the Nginx map. We're using the WPMUDev domain mapping plugin, which has recently allowed multiple domains to be added to a blog. It appears that they've let through blank domains, so when Nginx Helper creates the map it just leaves the domain blank on the line but has the blogid at the end of it still. This causes Nginx to give:
emerg] invalid number of the map parameters in /blog/location/wp-content/blogs.dir/1/nginx-helper/map.conf:8888
Once I remove the failed domain and it's regenerated it's fine.
I'm going to mention this to WPMUDev so they can fix it on their end, just thought you might like to know so you can build some validation into your plugin (if you haven't already).
Apart from that, the plugin is working really well on a quite large Multi-site installation (9000+ blogs), so thanks again!