HTTParty::Response fakes nil

HTTParty::Response sometimes looks nil but isn't. This makes for some interesting consequences and strange code in order to deal with them:

[1] pry(#Salesforce::Rest)> response
=> nil
[2] pry(#Salesforce::Rest)> response.code
=> 413
[4] pry(#Salesforce::Rest)> response.class
=> HTTParty::Response
[11] pry(#Salesforce::Rest)> response == nil
=> false
[12] pry(#Salesforce::Rest)> response.nil?
=> true
[13] pry(#Salesforce::Rest)> !!response
=> true

So in my code I have:
if !((200..299).include?(response.code))
if response.nil?
raise "SF ERROR #{response.code}" # fake nil, not a bug
else
raise "SF ERROR '#{response.message}': #{response.first['message']}"
end
end

As I see it there are two problems:

1. Response#inspect returns 'nil'
2. Response#nil? somehow returns true

I don't know why (2) happens, something to do with Ruby's internal implementation of .nil?, which is defined in Object.

Perhaps you can suggest an improvement for my error detecting code.

Start by reproducing the reported behavior with HTTParty::Response, then inspect its inspect and nil? behavior. The issue does not name files or tests; done should mean establishing the intended nil semantics and adding coverage for the observed response behavior.