Thanks for the link Jools. I noticed that you mention that error checking is limited MediaWiki::API->upload. Is this because you are having to parse the HTML returned for error messages?
It's because I don't parse the html returned at all. Basically if the upload does a redirect (code 302), then I assume everything was ok, else there was a failure, but I give no more details. I could parse the html returned but as this function is somewhat temporary until the API supports upload, it works enough for the time being. (My module was created to replace an old module we were using in some code to manage an area on our site http://www.exotica.org.uk/wiki/UnExoticA)
Best Regards
Jools