```ruby
class SessionsController < ApplicationController
  skip_before_action :authenticate_user_from_token!

  def create
    @user = User.find_for_database_authentication(email: params[:email])
    return invalid_login_attempt unless @user

    if @user.valid_password?(params[:password])
      sign_in :user, @user
      render json: @user, serializer: SessionsSerializer, root: nil
    else
      invalid_login_attempt
    end
  end

  private

  def invalid_login_attempt
    warden.custom_failure!
    render json: {error: 'sessions_controller.invalid_login_attempt'}, status: :unprocessable_entity
  end

end
```

Improve error message on login
user
```ruby
class SessionsController < ApplicationController
  skip_before_action :authenticate_user_from_token!

  def create
    @user = User.find_for_database_authentication(email: params[:email])
    return invalid_login_attempt unless @user

    if @user.valid_password?(params[:password])
      sign_in :user, @user
      render json: @user, serializer: SessionsSerializer, root: nil
    else
      invalid_login_attempt
    end
  end

  private

  def invalid_login_attempt
    warden.custom_failure!
    render json: {error: 'invalid login attempt'}, status: :unprocessable_entity
  end

end
```
assistant