The launcher does not work when I am updating the game. Usually, the process of updating takes 10-15 minutes, and afterwards you will notice that items might have bugs for a bit too. That is also normal. If you get this error, either run in offline mode, or wait 10-15 minutes and give it a try again.
As a rule of thumb, if you see some strange error, odds are that I'm either patching the game, or working on fixing it. If the error is still there after an hour, then feel free to contact me or post here with the error. Otherwise, you can assume it'll be dealt with relatively quickly.
Don't forget to scan through the posts here as well when you have an error. There's a good chance someone else has had the same error and received advice on how to fix it.