NameError: uninitialized constant RailsERD

This has been an occasional annoyance when setting up new Rails projects with the rails-erd gem.

The documentation for the gem is to add

gem 'rails-erd', :require=>false

into the Gemfile, and then run rails g erd:install to add the hook to run when a rails db:migrate is carried out.

I found that this creates /lib/tasks/auto_generate_diagram.rake containing

if Rails.env.development?
  RailsERD.load_tasks
end

One solution is to remove the :require=>false from the Gemfile, but apparently this may have an impact on efficiency rails erd issue 282.

I tried a slightly different approach, and changed /lib/tasks/auto_generate_diagram.rake to require the gem.

if Rails.env.development?
  require 'rails-erd'
  RailsERD.load_tasks
end