Fix some issues

src/Form/AdminUserType.php

@@ -48,7 +48,7 @@ class AdminUserType extends AbstractType
                 },
             ]);
 
-        if (!$UserGroup->getSubGroups()->isEmpty()) {
+        if ($UserGroup != null && !$UserGroup->getSubGroups()->isEmpty()) {
             $builder
             ->add('subGroups', EntityType::class, [
                 'class' => SubGroup::class,