fixup! fix #4479 by ensuring subquery in findNewIds never returns NULL

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

tests/Integration/Db/MessageMapperTest.php

@@ -145,7 +145,7 @@ public function testResetPreviewDataFlag(): void {
 	/**
 	 * Verify we still find the one message of the mailbox if the passed IDs do not exist
 	 */
-	public function testFindNewIdsCoalesence(): void {
+	public function testFindNewIdsCoalescence(): void {
 		$uid = time();
 		$mailbox = new Mailbox();
 		$mailbox->setId(1);