500 error returned when no data is POSTed to registration controller

[mchavarriagam]

Hello,

When posting an empty body to the Registration controller, a 500 error is returned:

NoMethodError in DeviseTokenAuth::RegistrationsController#create
undefined method `downcase' for nil:NilClass
Extracted source (around line #12):

  # honor devise configuration for case_insensitive_keys
  if resource_class.case_insensitive_keys.include?(:email)
    -> @resource.email = sign_up_params[:email].downcase
  else
    @resource.email = sign_up_params[:email]
  end

I'm currently working on an API which uses DTA so I have no way of ensuring that the client will send proper sign up data in POST body. I can do a PR for this but I'd like to make sure I'm going the right way about it:

1. Adding before_filter on registrations_controller (validate_sign_up_body perhaps? only for post)
2. validate_sign_up_body returns 422 unprocessable entity + json errors: 'Please post proper sign up data in request body.' if sign_up_params is empty.

Does that sound good?

Cheers.

[mchavarriagam]

Thank you!