Prevent error if using paginator :none

The PR fixes a bug if you use `paginator :none` and have `config.top_level_meta_include_page_count` set to `true`.

Author: fsmanuel

lib/jsonapi/processor.rb

@@ -92,7 +92,7 @@ def find
                                                                 include_directives: include_directives)
       end
 
-      if (JSONAPI.configuration.top_level_meta_include_page_count && page_options[:record_count])
+      if (JSONAPI.configuration.top_level_meta_include_page_count && paginator && page_options[:record_count])
         page_options[:page_count] = paginator.calculate_page_count(page_options[:record_count])
       end
 

test/controllers/controller_test.rb

@@ -2881,6 +2881,18 @@ def test_books_page_count_in_meta
     assert_equal 'Book 0', json_response['data'][0]['attributes']['title']
   end
 
+  def test_books_no_page_count_in_meta_with_none_paginator
+    Api::V2::BookResource.paginator :none
+    JSONAPI.configuration.top_level_meta_include_page_count = true
+    assert_cacheable_get :index, params: {include: 'book-comments'}
+    JSONAPI.configuration.top_level_meta_include_page_count = false
+
+    assert_response :success
+    assert_nil json_response['meta']['page-count']
+    assert_equal 901, json_response['data'].size
+    assert_equal 'Book 0', json_response['data'][0]['attributes']['title']
+  end
+
   def test_books_record_count_in_meta_custom_name
     Api::V2::BookResource.paginator :offset
     JSONAPI.configuration.top_level_meta_include_record_count = true