[Bug] Error message "undefined method `gsub' for nil:NilClass" when attempting to store something.

[cli0]

I am running a Vagrant VM with Ubuntu 16.04 and I have set up fake-s3 in there. It's running per the default description in the readme. Then I run a simple bash script that runs a curl command that sends a .conf file to the fake-s3 storage.

In doing that, I get the following error:

[2018-03-11 15:28:39] ERROR NoMethodError: undefined method `gsub' for nil:NilClass
        /var/lib/gems/2.3.0/gems/fakes3-1.2.1/lib/fakes3/server.rb:290:in `do_POST'
        /usr/lib/ruby/2.3.0/webrick/httpservlet/abstract.rb:107:in `service'
        /usr/lib/ruby/2.3.0/webrick/httpserver.rb:140:in `service'
        /usr/lib/ruby/2.3.0/webrick/httpserver.rb:96:in `run'
        /usr/lib/ruby/2.3.0/webrick/server.rb:296:in `block in start_thread'

My bash script does not even use the gsub command anywhere in it. Can anyone help me figure this out?