Initialize @_request and @_response.

actionpack/lib/action_controller/metal.rb

@@ -85,6 +85,8 @@ def controller_name
     def initialize(*)
       @_headers = {"Content-Type" => "text/html"}
       @_status = 200
+      @_request = nil
+      @_response = nil
       super
     end
 
@@ -99,7 +101,7 @@ def params=(val)
     # Basic implementations for content_type=, location=, and headers are
     # provided to reduce the dependency on the RackDelegation module
     # in Renderer and Redirector.
-    
+
     def content_type=(type)
       headers["Content-Type"] = type.to_s
     end