Fallback to ActiveModel translations in EmailValidator

[yivo]

No description provided.

[booleanbetrayal]

I don't understand the context for this PR. Why would your DeviseTokenAuth localizations be missing?

[yivo]

DeviseTokenAuth doesn't have localizations for some languages. We can check if there other localizations for the same locale and with same meaning.
Please see example below.

Localizations we have:

en:
  errors:
    messages:
      invalid: 'is invalid'       # Rails default
    not_email: 'is not an email'  # DeviceTokenAuth

I18n.available_locales = [:en, :it] # Set available locales

# Testing with :en
I18n.locale = :en
I18n.t(:'errors.not_email')                                       # => "is not an email"
I18n.t(:'errors.messages.invalid')                                # => "is invalid"
I18n.t(:'errors.not_email', default: :'errors.messages.invalid')  # => "is not an email"

# Testing with :it (1)
I18n.locale = :it
I18n.t(:'errors.not_email')                                       # => "translation missing: it.errors.not_email"
I18n.t(:'errors.messages.invalid')                                # => "translation missing: it.errors.messages.invalid"
I18n.t(:'errors.not_email', default: :'errors.messages.invalid')  # => "translation missing: it.errors.not_email"

Lets add more localizations:

it:
  errors:
    messages:
      invalid: 'non è valido'     # We have defined this localization in out project

And test again:

# Testing with :it (2)
I18n.locale = :it
I18n.t(:'errors.not_email')                                       # => "translation missing: it.errors.not_email"
I18n.t(:'errors.messages.invalid')                                # => "non è valido"
I18n.t(:'errors.not_email', default: :'errors.messages.invalid')  # => "non è valido"

[booleanbetrayal]

Gotcha. Sorry for the delay!