Use built-in version comparison API.

Author: stas

lib/jsonapi/rails.rb

@@ -56,8 +56,8 @@ def self.add_errors_renderer!
         end
 
         details = {}
-        if ::Rails::VERSION::MAJOR >= 6 && ::Rails::VERSION::MINOR >= 1
-          resource.map do |error|
+        if ::Rails.gem_version >= Gem::Version.new('6.1')
+          resource.each do |error|
             attr = error.attribute
             details[attr] ||= []
             details[attr] << error.detail.merge(message: error.message)

spec/errors_spec.rb

@@ -56,7 +56,7 @@
           .to eq(Rack::Utils::HTTP_STATUS_CODES[422])
         expect(response_json['errors'][0]['source'])
           .to eq('pointer' => '/data/relationships/user')
-        if Rails::VERSION::MAJOR >= 6 && Rails::VERSION::MINOR >= 1
+        if Rails.gem_version >= Gem::Version.new('6.1')
           expect(response_json['errors'][0]['detail'])
             .to eq('User must exist')
         else