error must be 0

Signed-off-by: Maxence Lange <maxence@artificial-owl.com>

lib/Db/CacheDocumentsRequest.php

@@ -150,7 +150,8 @@ class CacheDocumentsRequest extends CacheDocumentsRequestBuilder {
 		$qb = $this->getCacheDocumentsSelectSql();
 		$this->limitToDBFieldEmpty($qb, 'local_copy');
 		$this->limitToCaching($qb, self::CACHE_TTL);
-
+		$this->limitToDBFieldInt($qb, 'error', 0);
+		
 		$documents = [];
 		$cursor = $qb->execute();
 		while ($data = $cursor->fetch()) {