chore(psalm): add expected error for CalDavBackend.getChangesForCalendar

Null is a valid return for getChangesForCalendar, but the SyncSupport interface is wrong in the bundled sabre/dav version.

Signed-off-by: Daniel Kesselberg <mail@danielkesselberg.de>

build/psalm-baseline.xml

@@ -155,6 +155,86 @@
       <code>$uris</code>
     </MoreSpecificImplementedParamType>
     <NullableReturnStatement>
+      <code><![CDATA[$this->atomic(function () use ($calendarId, $syncToken, $syncLevel, $limit, $calendarType, $table) {
+			// Current synctoken
+			$qb = $this->db->getQueryBuilder();
+			$qb->select('synctoken')
+				->from($table)
+				->where(
+					$qb->expr()->eq('id', $qb->createNamedParameter($calendarId))
+				);
+			$stmt = $qb->executeQuery();
+			$currentToken = $stmt->fetchOne();
+
+			if ($currentToken === false) {
+				return null;
+			}
+
+			$result = [
+				'syncToken' => $currentToken,
+				'added' => [],
+				'modified' => [],
+				'deleted' => [],
+			];
+
+			if ($syncToken) {
+				$qb = $this->db->getQueryBuilder();
+
+				$qb->select('uri', 'operation')
+					->from('calendarchanges')
+					->where(
+						$qb->expr()->andX(
+							$qb->expr()->gte('synctoken', $qb->createNamedParameter($syncToken)),
+							$qb->expr()->lt('synctoken', $qb->createNamedParameter($currentToken)),
+							$qb->expr()->eq('calendarid', $qb->createNamedParameter($calendarId)),
+							$qb->expr()->eq('calendartype', $qb->createNamedParameter($calendarType))
+						)
+					)->orderBy('synctoken');
+				if (is_int($limit) && $limit > 0) {
+					$qb->setMaxResults($limit);
+				}
+
+				// Fetching all changes
+				$stmt = $qb->executeQuery();
+				$changes = [];
+
+				// This loop ensures that any duplicates are overwritten, only the
+				// last change on a node is relevant.
+				while ($row = $stmt->fetch()) {
+					$changes[$row['uri']] = $row['operation'];
+				}
+				$stmt->closeCursor();
+
+				foreach ($changes as $uri => $operation) {
+					switch ($operation) {
+						case 1:
+							$result['added'][] = $uri;
+							break;
+						case 2:
+							$result['modified'][] = $uri;
+							break;
+						case 3:
+							$result['deleted'][] = $uri;
+							break;
+					}
+				}
+			} else {
+				// No synctoken supplied, this is the initial sync.
+				$qb = $this->db->getQueryBuilder();
+				$qb->select('uri')
+					->from('calendarobjects')
+					->where(
+						$qb->expr()->andX(
+							$qb->expr()->eq('calendarid', $qb->createNamedParameter($calendarId)),
+							$qb->expr()->eq('calendartype', $qb->createNamedParameter($calendarType))
+						)
+					);
+				$stmt = $qb->executeQuery();
+				$result['added'] = $stmt->fetchAll(\PDO::FETCH_COLUMN);
+				$stmt->closeCursor();
+			}
+			return $result;
+		}, $this->db)]]></code>
       <code>null</code>
     </NullableReturnStatement>
   </file>