refactor ShowExceptions' #call to use def-rescue instead of begin-rescue

actionpack/lib/action_dispatch/middleware/show_exceptions.rb

@@ -27,13 +27,10 @@ module ActionDispatch
     end
 
     def call(env)
-      begin
-        response = @app.call(env)
+      @app.call(env)
     rescue Exception => exception
       raise exception if env['action_dispatch.show_exceptions'] == false
-      end
-
-      response || render_exception(env, exception)
+      render_exception(env, exception)
     end
 
     private