Access the error_response in the middleware after method

Hi,
I'm maintaining a fork of this repos : https://github.com/aserafin/grape_logging

Since v0.14.1, Grape ensure that the middleware after method is always call even if an exception occurs. This is a great functionality for us because now we can log failed requests.

But when the @app.call(@env) fail here : https://github.com/ruby-grape/grape/blob/master/lib/grape/middleware/base.rb#L30
then the call to the response method in the middleware will fail because it will try to to that @app_response[2] at this line : https://github.com/ruby-grape/grape/blob/master/lib/grape/middleware/base.rb#L58 but @app_response is nil.

My question is: how do I access to the error_response (or the thing that contains the error answer) in my middleware when an error!("something", 404) is called in the endpoint ? Is it possible ?

Start with lib/grape/middleware/base.rb at the referenced lines 30 and 58, then trace how the middleware after method handles failures from @app.call(@env). Determine how an error_response from error!("something", 404) should be exposed to middleware and add coverage for that failure path; done means the middleware can access the error response without response failing.