NC12.0.4 - undefined index in UpdateChecker.php #7442

Expected behavior

No errors should belogged.

Current behavior

The following errors were logged after upgrading from v12.0.3 to v12.0.4:

Error	PHP	Undefined index: autoupdater at ../apps/updatenotification/lib/UpdateChecker.php#49
Error	PHP	Undefined index: url at ../apps/updatenotification/lib/UpdateChecker.php#53

Steps to reproduce

1. Upgrade to v12,0.4 and check the log file.

Environment

Server Configuration

OS: Linux 3.16.50
Web server: Apache2 2.4.29
Database: MariaDB 10.0.32
PHP version: 5.6.29
Nextcloud version: 12.0.4

Client Configuration

Browser: Mozilla Firefox 57.0.2
Operating system: Windows 7