```ruby
class ApplicationController < ActionController::Base
  protect_from_forgery with: :exception
  before_action :authenticate_user!
  before_action :configure_permitted_parameters, if: :devise_controller?


  protected

  def configure_permitted_parameters
    devise_parameter_sanitizer.permit(:sign_in) do |user_params|
      user_params.permit(:username, :email)
    end
  end

end
```

Remove empty line at ApplicationController
user
```ruby
class ApplicationController < ActionController::Base
  protect_from_forgery with: :exception
  before_action :authenticate_user!
  before_action :configure_permitted_parameters, if: :devise_controller?

  protected

  def configure_permitted_parameters
    devise_parameter_sanitizer.permit(:sign_in) do |user_params|
      user_params.permit(:username, :email)
    end
  end

end
```
assistant