Add error suppressed by Grape::Middleware::Error to rack env(like action_dispatch.exception)

[tevvi]

Rails add suppressed errors to rack envs, but i didnt found suppressed errors from grape in rack env
So we wrote monkeypatch grape to access suppressed errors by Grape::Middleware::Error:

# grape 1.8.0 
module GrapeMiddlewareErrorPatch
  def run_rescue_handler(handler, e)
    @env['grape.exception'] = e
    super(handler, e)
  end
end

if defined?(Grape::Middleware::Error)
  Grape::Middleware::Error.prepend(GrapeMiddlewareErrorPatch)
end

So may be add this line to gem?)

[dblock]

Would love some more info about what's going on here and why Rails does that, and yes please do open a PR?

[tevvi]

There we just add error to rack env to get access to this error from rack middlewares. For example we want to log input http requests? and we think it is will be helpful to log error happened in any framework. But usually frameworks suppress all errors to return always rack response [status, headers, body]
But rails add suppressed error to rack env, so it is easy to access errors from rails:
https://github.com/rails/rails/blob/529f933fc8b13114d308dd0752f76a9e293c8537/actionpack/lib/action_dispatch/middleware/show_exceptions.rb#L37

I will open MR for this line on 4-5 October