Property not found in \Illuminate\Contracts\Auth\Authenticatable|nul - variables

Question

Hello I use laravel 8 and backpack 4.1. I get an error: Property not found in \Illuminate\Contracts\Auth\Authenticatable|null, I have user_id in the table 'tenants'. Has somebody an idea, why the variable $ccu is null.
User.php:
public static function getUser()
{
return Auth::guard('backpack')->user();
}
public function tenant(): BelongsTo
{
return $this->belongsTo(Tenant::class);
}
Tenant.php:
vpublic function ccus(): HasMany
{
return $this->hasMany(Ccu::class);
}
public function users():hasMany
{
return $this->hasMany(User::class, 'user_id');
}
DashboardUserController:
public function index()
{
if (backpack_user()->hasRole('admin')) {
$this->data['title'] = trans('backpack::base.dashboard');
$this->data['breadcrumbs'] = [
trans('backpack::crud.admin') => backpack_url('dashboard'),
trans('backpack::base.dashboard') => false,
];
return view('dashboard', $this->data);
} else {
$user=User::getUser();
$ccu = $user->tenant->ccus()->get();
$ccuDiagram = new CcuDiagram($ccu);
$dataForGauge = CcuDiagram::getData($ccu);
$service = Service::find(1);
return view('ccu', ["dataForGauge" => $dataForGauge, "service" => $service]);
}
}
Ccu.php
public function tenant(): HasOne
{
return $this->hasOne(Tenant::Class);
}