"Interface 'Illuminate\Contracts\Auth\Access\Gate' not found" I can't figure out what is wrong here

So basically I'm building an application using Laravel 5.6, under php 7.1.2, and I got this error:

Symfony \ Component \ Debug \ Exception \ FatalErrorException (E_UNKNOWN) Interface 'Illuminate\Contracts\Auth\Access\Gate' not found

So obviously I checked the incriminated file and stumbled on this piece of code which I don't understand in Illuminate\Contracts\Auth\Access\Gate.php

use Illuminate\Contracts\Auth\Access\Gate as GateContract;

class Gate implements GateContract {

I don't understand why the file is using itself, and why the Gate class is trying to implement itself despite the fact that it's defined as a class and not an interface. Thus I don't understand how I am supposed to solve this mess.

If anyone could shed some light on this I would be grateful.

via Chebli Mohamed