Ensure status param takes precedence over error.status

[jasonkarns]

I believe this is a bug.

Prior to this change:

_err = new Error()
_err.status = 404
err = createError(500, _err) // err.status == 404

After this change (no tests modified):

_err = new Error()
_err.status = 404
err = createError(500, _err) // err.status == 500

[dougwilson]

Imo it is not a bug, orgerwide if you wrap an error from thos module with a different code, the error name and other props will not reflect correctly.

[dougwilson]

I.e. you can end up with err instanceof NotFoundError but err.statusCode === 410 witch is not desired.

[jasonkarns]

Closing as works-as-designed.

#37 now includes a new test to actually verify/document this behavior as intended. 91a7445#diff-c1129c8b045390789fa8ff62f2c6b4a9R180