Testing 500 response

[jema28]

500 error responses usually occur when a server fails to do something ie. when one of your functions in a controller (or other parts of the app) error so it would better to do a 500 test in those functions instead of here https://github.com/fac-14/Vent-Bot/blob/master/src/controllers/router.js#L24-L33. Let me know if that makes sense!