Fix tests

Signed-off-by: Roeland Jago Douma <roeland@famdouma.nl>

apps/dav/lib/Connector/Sabre/ObjectTree.php

@@ -156,7 +156,7 @@ class ObjectTree extends CachingTree {
 			try {
 				$info = $this->fileView->getFileInfo($path);
 
-				if ($info->getStorage()->instanceOfStorage(FailedStorage::class)) {
+				if ($info instanceof \OCP\Files\FileInfo && $info->getStorage()->instanceOfStorage(FailedStorage::class)) {
 					throw new StorageNotAvailableException();
 				}
 			} catch (StorageNotAvailableException $e) {

apps/dav/tests/unit/Connector/Sabre/ObjectTreeTest.php

@@ -174,6 +174,8 @@ class ObjectTreeTest extends \Test\TestCase {
 		$fileInfo->expects($this->once())
 			->method('getName')
 			->will($this->returnValue($outputFileName));
+		$fileInfo->method('getStorage')
+			->willReturn($this->createMock(\OC\Files\Storage\Common::class));
 
 		$view->expects($this->once())
 			->method('getFileInfo')