Catch NotFoundException and return no quota information which simply reflects the current state - no file storage has been initialized for the user.

lib/private/encryption/manager.php

@@ -151,7 +151,7 @@ class Manager implements IManager {
 			if (isset($this->encryptionModules[$moduleId])) {
 				return call_user_func($this->encryptionModules[$moduleId]['callback']);
 			} else {
-				$message = "Module with id: $moduleId does not exists.";
+				$message = "Module with id: $moduleId does not exist.";
 				$hint = $this->l->t('Module with id: %s does not exist. Please enable it in your apps settings or contact your administrator.', [$moduleId]);
 				throw new Exceptions\ModuleDoesNotExistsException($message, $hint);
 			}