Properly set exception in FailedStorage

apps/files_external/lib/config/configadapter.php

@@ -35,6 +35,7 @@ use OCA\Files_external\Service\UserStoragesService;
 use OCA\Files_External\Service\UserGlobalStoragesService;
 use OCA\Files_External\Lib\StorageConfig;
 use OCA\Files_External\Lib\FailedStorage;
+use OCP\Files\StorageNotAvailableException;
 
 /**
  * Make the old files_external config work with the new public mount config api
@@ -134,7 +135,9 @@ class ConfigAdapter implements IMountProvider {
 			try {
 				$availability = $impl->getAvailability();
 				if (!$availability['available'] && !Availability::shouldRecheck($availability)) {
-					$impl = new FailedStorage(['exception' => null]);
+					$impl = new FailedStorage([
+						'exception' => new StorageNotAvailableException('Storage with mount id ' . $storage->getId() . ' is not available')
+					]);
 				}
 			} catch (\Exception $e) {
 				// propagate exception into filesystem

apps/files_external/lib/failedstorage.php

@@ -39,6 +39,9 @@ class FailedStorage extends Common {
 	 */
 	public function __construct($params) {
 		$this->e = $params['exception'];
+		if (!$this->e) {
+			throw new \InvalidArgumentException('Missing "exception" argument in FailedStorage constructor');
+		}
 	}
 
 	public function getId() {