Fix for has_one relationships where related record does not exist

[lgebhardt]

No description provided.

[joegaudet]

Looks good to me @lgebhardt, did you want me to try it on my spike branch and see if it fixes my issue?

[lgebhardt]

@joegaudet If you could test it that would be appreciated. There was a definite issue when the new tests were added so I'm optimistic it will fix your issue, but knowing for sure would be best.

[joegaudet]

@lgebhardt seems I'm still seeing the same stack trace:

NoMethodError
undefined method `_type' for NilClass:Class
/Users/joegaudet/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/jsonapi-resources-0.9.0/lib/jsonapi/resource_serializer.rb:499:in `add_resource'
/Users/joegaudet/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/jsonapi-resources-0.9.0/lib/jsonapi/resource_serializer.rb:347:in `block (2 levels) in cached_relationships_hash'
/Users/joegaudet/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/jsonapi-resources-0.9.0/lib/jsonapi/resource_serializer.rb:346:in `each'
/Users/joegaudet/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/jsonapi-resources-0.9.0/lib/jsonapi/resource_serializer.rb:346:in `block in cached_relationships_hash'
/Users/joegaudet/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/jsonapi-resources-0.9.0/lib/jsonapi/resource_serializer.rb:326:in `each'
/Users/joegaudet/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/jsonapi-resources-0.9.0/lib/jsonapi/resource_serializer.rb:326:in `cached_relationships_hash'
/Users/joegaudet/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/jsonapi-resources-0.9.0/lib/jsonapi/resource_serializer.rb:154:in `object_hash'
/Users/joegaudet/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/jsonapi-resources-0.9.0/lib/jsonapi/resource_serializer.rb:506:in `add_resource'
/Users/joegaudet/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/jsonapi-resources-0.9.0/lib/jsonapi/resource_serializer.rb:196:in `process_source_objects'
/Users/joegaudet/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/jsonapi-resources-0.9.0/lib/jsonapi/resource_serializer.rb:193:in `block in process_source_objects'
/Users/joegaudet/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/jsonapi-resources-0.9.0/lib/jsonapi/resource_serializer.rb:193:in `each'
/Users/joegaudet/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/jsonapi-resources-0.9.0/lib/jsonapi/resource_serializer.rb:193:in `process_source_objects'
/Users/joegaudet/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/jsonapi-resources-0.9.0/lib/jsonapi/resource_serializer.rb:53:in `serialize_to_hash'
/Users/joegaudet/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/jsonapi-resources-0.9.0/lib/jsonapi/response_document.rb:111:in `results_to_hash'
/Users/joegaudet/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/jsonapi-resources-0.9.0/lib/jsonapi/response_document.rb:12:in `contents'
/Users/joegaudet/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/jsonapi-resources-0.9.0/lib/jsonapi/acts_as_resource_controller.rb:226:in `render_results'
/Users/joegaudet/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/jsonapi-resources-0.9.0/lib/jsonapi/acts_as_resource_controller.rb:78:in `process_request'
/Users/joegaudet/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/jsonapi-resources-0.9.0/lib/jsonapi/acts_as_resource_controller.rb:16:in `index'