fix: load groups in user only mode

without this fix, PerunEntitlement does not work with PerunIdentity in user-only mode

lib/Auth/Process/PerunIdentity.php

@@ -272,9 +272,8 @@ class PerunIdentity extends \SimpleSAML\Auth\ProcessingFilter
             $this->registerUrl = $request['SPMetadata'][self::REGISTER_URL];
         }
 
-        $groups = [];
-
         $user = $this->adapter->getPerunUser($idpEntityId, $uids);
+
         if ($this->useAdditionalIdentifiersLookup && $user === null) {
             $additionalIdentifiers =
                 $request[PerunConstants::ATTRIBUTES][$this->additionalIdentifiersAttribute] ?? null;
@@ -287,16 +286,16 @@ class PerunIdentity extends \SimpleSAML\Auth\ProcessingFilter
             $user = $this->adapter->getPerunUserByAdditionalIdentifiers($idpEntityId, $additionalIdentifiers);
         }
 
+        $groups = $this->entityIdAttr === null ? $this->adapter->getUsersGroupsOnFacility(
+            $this->spEntityId,
+            $user->getId()
+        ) : $this->adapter->getUsersGroupsOnFacility($this->spEntityId, $user->getId(), $this->entityIdAttr);
+
         if ($this->mode === self::MODE_FULL) {
             $this->getSPAttributes($this->spEntityId);
 
             $this->checkMemberStateDefaultVo($request, $user, $uids);
 
-            $groups = $this->entityIdAttr === null ? $this->adapter->getUsersGroupsOnFacility(
-                $this->spEntityId,
-                $user->getId()
-            ) : $this->adapter->getUsersGroupsOnFacility($this->spEntityId, $user->getId(), $this->entityIdAttr);
-
             if ($this->checkGroupMembership && empty($groups)) {
                 if ($this->allowRegistrationToGroups) {
                     $vosForRegistration = $this->getVosForRegistration($user);