Rails 5 resque error 'cannot load such file -- rack/showexceptions'

I decided to setup some background jobs for an app I've been working on, and decided to go with Resque for handling the jobs. I wanted to be able to run the resque jobs as rake tasks, so I added the appropriate lines to my Rakefile, but when starting my Rails server - I got an error:

! Unable to load application: LoadError: cannot load such file -- rack/showexceptions

After a little Googling, I came across this issue posted on the Sidekiq Github account. The recommendation was to add the Sinatra gem, which worked for Sidekiq users. I gave it a try, and that fixed the error for me as well:

gem 'sinatra', github: 'sinatra'

Just thought I'd throw this up in case anyone else came across this issue.

Cheers