fix(files_sharing): filter out invalid shareWith in sharee API

Signed-off-by: skjnldsv <[email protected]>

apps/files_sharing/lib/Controller/ShareesAPIController.php

@@ -257,7 +257,7 @@ private function getAllSharees(string $user, array $shareTypes): ISearchResult {
 			$sharees = $this->getAllShareesByType($user, $shareType);
 			$shareTypeResults = [];
 			foreach ($sharees as [$sharee, $displayname]) {
-				if (!isset($this->searchResultTypeMap[$shareType])) {
+				if (!isset($this->searchResultTypeMap[$shareType]) || empty($sharee)) {
 					continue;
 				}