Initialize collectionTypes variable as false

lib/public/share.php

@@ -661,6 +661,7 @@ class Share {
 			}
 		}
 		$backend = self::getBackend($itemType);
+		$collectionTypes = false;
 		// Get filesystem root to add it to the file target and remove from the
 		// file source, match file_source with the file cache
 		if ($itemType == 'file' || $itemType == 'folder') {