Checkmk Werk 14713: <tt>graylog_failures</tt>: Fix crash with <tt>JSONDecodeError</tt>

ID: 14713 Title: <tt>graylog_failures</tt>: Fix crash with <tt>JSONDecodeError</tt> Component: Checks & agents Level: 1 Class: Bug fix Version: 2.2.0i1 Depending on the failures reported by the Graylog API, the check plugin <tt>graylog_failures</tt> crashed with C+: JSONDecodeError (Expecting value: line 1 column 1 (char 0)) C-: