Fix failing cascade exception.

actionpack/lib/action_dispatch/middleware/debug_exceptions.rb

@@ -15,6 +15,7 @@ module ActionDispatch
       begin
         response = @app.call(env)
 
+        # TODO: Maybe this should be in the router itself
         if response[1]['X-Cascade'] == 'pass'
           raise ActionController::RoutingError, "No route matches [#{env['REQUEST_METHOD']}] #{env['PATH_INFO'].inspect}"
         end
@@ -22,7 +23,7 @@ module ActionDispatch
         raise exception if env['action_dispatch.show_exceptions'] == false
       end
 
-      response ? response : render_exception(env, exception)
+      exception ? render_exception(env, exception) : response
     end
 
     private

actionpack/lib/action_dispatch/middleware/show_exceptions.rb

@@ -40,7 +40,7 @@ module ActionDispatch
         raise exception if env['action_dispatch.show_exceptions'] == false
       end
 
-      response ? response : render_exception_with_failsafe(env, exception)
+      response || render_exception_with_failsafe(env, exception)
     end
 
     private

actionpack/test/dispatch/debug_exceptions_test.rb

@@ -11,6 +11,8 @@ class DebugExceptionsTest < ActionDispatch::IntegrationTest
       env['action_dispatch.show_detailed_exceptions'] = @detailed
       req = ActionDispatch::Request.new(env)
       case req.path
+      when "/pass"
+        [404, { "X-Cascade" => "pass" }, []]
       when "/not_found"
         raise ActionController::UnknownAction
       when "/runtime_error"
@@ -46,6 +48,13 @@ class DebugExceptionsTest < ActionDispatch::IntegrationTest
     end
   end
 
+  test 'raise an exception on cascade pass' do
+    @app = ProductionApp
+    assert_raise ActionController::RoutingError do
+      get "/pass", {}, {'action_dispatch.show_exceptions' => true}
+    end
+  end
+
   test "rescue with diagnostics message" do
     @app = DevelopmentApp