Error message when registration fails

[chiptopher]

Feature Request

When a registration fails, pop up an error message saying that it failed.

Optional user story format:

Context

It's hard to know if the request is just lagging or if the request has failed when attempting to register.

Acceptance Criteria

When the registration fails because the account is already claimed, a box should pop up above the register button saying:

Account already claimed.

When the registration fails for any other reason, a box should pop up above the registration button that says:

Registration failed. Please try again.