Rails rake assets:precompile for production
Old question but the accepted answer doesn't really answer the question - and I just found this in a search so I guess it's relevant.
The reason for the error is that gem 'pg' is in the production gem group.
When you run rake assets:precompile the production environment is accessed. So it is trying to load the production environment but you don't have all of the dependencies installed.
Running RAILS_ENV=production bundle exec rails server would probably give you a similar error.
I can think of two different solutions
1) Look to see if you have a .bundle/config file in your app's root. If you do, check if it says WITHOUT :production or similar. Either remove that line or the whole .bundle directory and run bundle again.
2) in Gemfile
gem :development, :production do gem 'pg'endwhile removing the :production group
run bundle again
Sorry to bring up old stuff...