Can't access Mattermost (Account Exists and Doesn't Exist at the same time)

Hey all,

I was on the chat to learn about the development process and hopefully contribute once I can actually write in Rust. But I can’t login anymore on either the desktop or web apps.

Here’s the second error:

Check the placeholder text on login form. It says you should use your e-mail address to sign in, not your username. Username sign-ins doesn’t seem to be enabled on this server.