Wrong error triggered when number of fields exceed maxCount with .array(fieldname[, maxCount])

I use `upload.array('files', 5)`.

When I send from 1 to 5 files, everything works great !
But when I send 6 files I got the following error :
`{ [Error: Unexpected field] code: 'LIMIT_UNEXPECTED_FILE', field: 'files', storageErrors: [] }`

According to [make-error.js](https://github.com/expressjs/multer/blob/master/lib/make-error.js) I should get this code `LIMIT_FILE_COUNT` right ? Or am I missing something ?

The report uses upload.array('files', 5) and points to lib/make-error.js. Reproduce the six-file upload, then trace how the array limit is handled and compare the emitted error with LIMIT_FILE_COUNT. Done means the six-file case reports the intended code and the existing behavior remains correct for one through five files.

Written by the indexing model from the issue text.