has it been defined as an auto-increment?

You mean, in the laravel project or in the database?
I didn't define anything beacause the database was already created.

Here is my Registrar class:

class Registrar implements RegistrarContract {

/**
 * Get a validator for an incoming registration request.
 *
 * @param  array  $data
 * @return \Illuminate\Contracts\Validation\Validator
 */
public function validator(array $data)
{
	return Validator::make($data, [
		'name' => 'required|max:255',
		'password' => 'required|confirmed|min:6',
	]);
}

/**
 * Create a new user instance after a valid registration.
 *
 * @param  array  $data
 * @return User
 */
public function create(array $data)
{
	return User::create([
		'login' => $data['name'],
		'pass' => bcrypt($data['password']),
	]);
}

}

Thank you!