title: Devise login error for invalid email or password is not working in rails
body: <p>i have a devise <code>user</code> model. when the <code>user</code> enters wrong <code>password</code> its redirecting back to the login page by showing invalid email or password, this is working fine. but when the user enters the wrong <code>email</code> then i am not getting the same error. i am getting a different <code>error</code> </p>
  
  <pre><code>I18n::MissingInterpolationArgument at /users/sign_in
  missing interpolation argument :authentication_keys in "Invalid %{authentication_keys} or password." ({:resource_name=&gt;:user} given)
  </code></pre>
  
  <p>. in my user model i have a username field(this is unique). in my case a user can login with both <code>username</code> and <code>email</code>. is this <code>customisation</code> created any issue? this is my <code>devise.en.yml</code> file .</p>
  
  <pre><code># Additional translations at https://github.com/plataformatec/devise/wiki/I18n
  
  en:
    devise:
      confirmations:
        confirmed: "Your email address has been successfully confirmed."
        send_instructions: "You will receive an email with instructions for how to confirm your email address in a few minutes."
        send_paranoid_instructions: "If your email address exists in our database, you will receive an email with instructions for how to confirm your email address in a few minutes."
      failure:
        already_authenticated: "You are already signed in."
        inactive: "Your account is not activated yet."
        invalid: "Invalid email or password."
        locked: "Your account is locked."
        last_attempt: "You have one more attempt before your account is locked."
        not_found_in_database: "Invalid %{authentication_keys} or password."
        timeout: "Your session expired. Please sign in again to continue."
        unauthenticated: "You need to sign in or sign up before continuing."
        unconfirmed: "You have to confirm your email address before continuing."
      mailer:
        confirmation_instructions:
      subject: "Confirmation instructions"
        reset_password_instructions:
      subject: "Reset password instructions"
        unlock_instructions:
      subject: "Unlock instructions"
        password_change:
      subject: "Password Changed"
      omniauth_callbacks:
        failure: "Could not authenticate you from %{kind} because \"%{reason}\"."
        success: "Successfully authenticated from %{kind} account."
      passwords:
        no_token: "You can't access this page without coming from a password reset email. If you do come from a password reset email, please make sure you used the full URL provided."
        send_instructions: "You will receive an email with instructions on how to reset your password in a few minutes."
        send_paranoid_instructions: "If your email address exists in our database, you will receive a password recovery link at your email address in a few minutes."
        updated: "Your password has been changed successfully. You are now signed in."
        updated_not_active: "Your password has been changed successfully."
      registrations:
        destroyed: "Bye! Your account has been successfully cancelled. We hope to see you again soon."
        signed_up: "Welcome! You have signed up successfully."
        signed_up_but_inactive: "You have signed up successfully. However, we could not sign you in because your account is not yet activated."
        signed_up_but_locked: "You have signed up successfully. However, we could not sign you in because your account is locked."
        signed_up_but_unconfirmed: "A message with a confirmation link has been sent to your email address. Please follow the link to activate your account."
        update_needs_confirmation: "You updated your account successfully, but we need to verify your new email address. Please check your email and follow the confirm link to confirm your new email address."
        updated: "Your account has been updated successfully."
      sessions:
        signed_in: "Signed in successfully."
        signed_out: "Signed out successfully."
        already_signed_out: "Signed out successfully."
      unlocks:
        send_instructions: "You will receive an email with instructions for how to unlock your account in a few minutes."
        send_paranoid_instructions: "If your account exists, you will receive an email with instructions for how to unlock it in a few minutes."
        unlocked: "Your account has been unlocked successfully. Please sign in to continue."
    errors:
      messages:
        already_confirmed: "was already confirmed, please try signing in"
        confirmation_period_expired: "needs to be confirmed within %{period}, please request a new one"
        expired: "has expired, please request a new one"
        not_found: "not found"
        not_locked: "was not locked"
        not_saved:
      one: "1 error prohibited this %{resource} from being saved:"
      other: "%{count} errors prohibited this %{resource} from being saved:"
  </code></pre>
  
  <p>these are the devise and rails versions in <code>gemfile.lock</code> file.</p>
  
  <pre><code>    devise (3.2.4)
      devise-async (0.9.0)
      devise (~&gt; 3.2)
      devise
      devise-async
  
      rails (4.1.5)
  </code></pre>