fix(controller): Check if the group already exist before rendering

It's possible for a group not to exist, but still to be attached to a
groupfolder.
This change allows for this issue.

lib/Controller/WorkspaceController.php

@@ -196,8 +196,24 @@ public function findAll(): JSONResponse {
 			) : $workspace;
 
 			$gids = array_keys($space['groups'] ?? []);
-			$groups = array_map(fn ($gid) => $this->groupManager->get($gid), $gids);
-
+
+            $groups = [];
+
+            foreach ($gids as $gid) {
+                $group = $this->groupManager->get($gid);
+
+                if (is_null($group)) {
+                    $this->logger->warning(
+                        "Be careful, the $gid group is not exist in the oc_groups table."
+                        . " But, it's present in the oc_group_folders_groups table."
+                        .  "It necessary to recreate it with the occ command."
+                    );
+                    continue;
+                }
+
+                $groups[] = $group;
+            }
+
 			$space['groups'] = GroupFormatter::formatGroups($groups);
 			$space['users'] = $this->workspaceService->addUsersInfo($space);