This fixes an error message on app startup about autoloaded
constants:
> DEPRECATION WARNING: Initialization autoloaded the constants ActionText::ContentHelper and ActionText::TagHelper.
The reason for this error is that the Mailjet gem forces the
immediate loading of `action_mailer`. Which leads to the
following sequence of events:
On app init, when bundler requires all the gems in the Gemfile:
- The Mailjet gem is required,
- It loads `ActionMailer::Base`.
Later, when Rails initializes itself:
- `ActionText` creates an `action_text.helpers` initializer,
- This initializer register hooks to add `ActionText` helpers
when either `action_controller_base` or `action_mailer` are loaded,
- But as `action_mailer` has already been loaded, the hook is trigerred
immediately,
- ActiveSupport::Dependencies notices `ActionText` constants do not
exist yet, auto-load them, and add the constants to
`ActiveSupport::Dependencies.autoloaded_constants`.
And even later, at the end of the Rails initialization process:
- The `:warn_if_autoloaded` initializer is run,
- It notices that `autoloaded_constants` is not empty, and prints the
warning message.
See https://github.com/mailjet/mailjet-gem/issues/213
