Eager load in a to_prepare block

[fxn]

There is an engine initializer doing this:

Rails.application.eager_load!
ContentfulModel::Base.descendents.each do |klass|
  klass.send(:add_entry_mapping)
end

Rails applications cannot load application code so early. If you change a content model and reload, nobody is invoking #add_entry_mapping on it again. In Rails 7 this is not even possible.

That should be done in a to_prepare block, so that it runs when things are ready on boot, and also on every reload.

(This logic is not related to Zeitwerk, though Rails and Zeitwerk are being polished to uncover latent issues like this one.)