Errors do not end up in the express middleware chain

### Description

Errors that take place in the middleware does not get put into the express middleware chain. Currently the middleware will simply call `res.send` to send the notice to the end user. 

### Reproduction

Just example code without `req.user` property will cause plaintext "Unauthorized" to be sent to the browser. 

### Environment

- **Version of this library used:** 3.4.1
