Revert "fix: skip class caching if Rails has it disabled"

This reverts commit 89e69e6.

Author: adamkiczula

lib/jsonapi/resource_common.rb

@@ -541,27 +541,19 @@ def rebuild_relationships(relationships)
       end
 
       def resource_klass_for(type)
+        @_resource_type_to_class_cache ||= {}
         type = type.underscore
 
-        if ::Rails.application.config.cache_classes
-          @_resource_type_to_class_cache ||= {}
-          @_resource_type_to_class_cache.fetch(type) do
-            @_resource_type_to_class_cache[type] = _resource_klass_for(type)
-          end
-        else
-          _resource_klass_for(type)
-        end
-      end
-
-      def _resource_klass_for(type)
-        type_with_module = type.start_with?(module_path) ? type : module_path + type
+        @_resource_type_to_class_cache.fetch(type) do
+          type_with_module = type.start_with?(module_path) ? type : module_path + type
 
-        resource_name = _resource_name_from_type(type_with_module)
-        resource_klass = resource_name.safe_constantize if resource_name
-        if resource_klass.nil?
-          fail NameError, "JSONAPI: Could not find resource '#{type}'. (Class #{resource_name} not found)"
+          resource_name = _resource_name_from_type(type_with_module)
+          resource_klass = resource_name.safe_constantize if resource_name
+          if resource_klass.nil?
+            fail NameError, "JSONAPI: Could not find resource '#{type}'. (Class #{resource_name} not found)"
+          end
+          @_resource_type_to_class_cache[type] = resource_klass
         end
-        resource_klass
       end
 
       def resource_klass_for_model(model)