Requesting unknown file type returns Ruby object w/ address

Hello sec folks, requesting a report you are **not allowed** to acccess along with an **unhandled filetype extension** discloses a [Mime::NullType](http://edgeapi.rubyonrails.org/classes/Mime/NullType.html) Ruby object representation with a corresponding memory address. Example: https://hackerone.com/reports/1337.foo Request: ```http GET /reports/1337.foo HTTP/1.1 Host: hackerone.com ``` Response: ```http HTTP/1.1 401 Unauthorized .... Content-Type: #<Mime::NullType:0x007f3588fe32c8>; charset=utf-8 ... ``` Cheers!