I've got an API mode Rails 5 app that won't let me run rake routes or rails s. The error I get is:

$ rake routes
rake aborted!
LoadError: Could not load the 'listen' gem. Add `gem 'listen'` to the development group of your Gemfile
.../config/environment.rb:5:in `'
LoadError: cannot load such file -- listen
.../config/environment.rb:5:in `'
Tasks: TOP => routes => environment
(See full trace by running task with --trace)
I've verified that listen is in the development group in my Gemfile:

group :development do
gem 'listen', '~> 3.1.5'
# Spring speeds up development by keeping your application running in the background. Read more: HTTPS://github.com/rails/spring
gem 'spring'
gem 'spring-watcher-listen', '~> 2.0.0'
end
And that it's in my Gemfile.lock:

$ cat Gemfile.lock | grep 'listen'
listen (3.1.5)
spring-watcher-listen (2.0.0)
listen (>= 2.7, < 4.0)
listen (~> 3.1.5)
spring-watcher-listen (~> 2.0.0)
I've bundle updated, and bundle installed, and verified that gem install listen works. This was working earlier this week, but I'm not having luck going back through my commits.

$ ruby -v
ruby 2.2.3p173 (2015-08-18 revision 51636) [x86_64-darwin14]
I don't see it in vendor/cache but I'm not sure what to MAKE of that...

$ bundle PACKAGE | grep 'listen'
Appreciate the help!

Update:

I can "fix" the problem by putting gem 'listen', '~> 3.1.5' in the global Gemfile (and removing it from :development). Then all the errors go away and EVERYTHING works, but that seems wrong.