This is an awesome project. Thanks for this.
If I use web-irc to connect to a server with nick "lance" and any channel(s) and that nick is already in use I won't get any warning messages I'll just be presented with a web-irc UI with only a status tab which doesn't respond to any commands. I won't have joined any channels. If I try to /join #channel nothing will happen in the UI.
I was able to reproduce this using the only 2 servers I tried with, my own IRC server, and irc.freenode.net
This is easy to work around when connecting to my private IRC server, I just won't use a nickname I know is already in use.
If you need any details from me, logs, whatever, just ask. Thanks.