Workaround for https://github.com/smartinez87/exception_notification/pull/504

application.rb

# ...

# Require the gems listed in Gemfile, including any gems
# you've limited to :test, :development, or :production.
Bundler.require(*Rails.groups)

# TODO: remove once gems no longer need it. See required file for details.
# Patches Rails before initializing Gems. Also covers rake tasks that don't depend on :environment.
if Rails.gem_version >= Gem::Version.new('6.1') # Forward-port methods removed in 6.1
  require_relative "../lib/extensions/core_ext/module/introspection"
end

# ...

introspection.rb

# frozen_string_literal: true

# Restores `Module#parent_name`, `Module#parent` and `Module#parents`.
# Removed in Rails 6.1 by https://github.com/rails/rails/commit/167b4153cac0069a21e0bb9689cb16f34f6abbaa
#
# Still required by exception_notifier:
# - https://github.com/smartinez87/exception_notification/pull/504
class Module
  def parent_name
    ActiveSupport::Deprecation.warn(<<-MSG.squish)
      `Module#parent_name` has been renamed to `module_parent_name`.
      `parent_name` is deprecated and will be removed in Rails 6.1.
    MSG
    module_parent_name
  end

  def parent
    ActiveSupport::Deprecation.warn(<<-MSG.squish)
      `Module#parent` has been renamed to `module_parent`.
      `parent` is deprecated and will be removed in Rails 6.1.
    MSG
    module_parent
  end

  def parents
    ActiveSupport::Deprecation.warn(<<-MSG.squish)
      `Module#parents` has been renamed to `module_parents`.
      `parents` is deprecated and will be removed in Rails 6.1.
    MSG
    module_parents
  end
end

if Gem.loaded_specs['exception_notification'].version > Gem::Version.new('4.4.3')
  ActiveSupport::Deprecation.warn "exception_notification has been updated, so this patch may no longer be necessary"
end