Checkmk Werk 13517: <tt>gude_pdu</tt>: Fix errors during discovery and checking

ID: 13517 Title: <tt>gude_pdu</tt>: Fix errors during discovery and checking Component: Checks & agents Level: 1 Class: Bug fix Version: 2.1.0i1 The check plugins <tt>gude_pdu_8301</tt> and <tt>gude_pdu_8310</tt> crashed with "TypeError: list indices must be integers or slices, not str" for already discovered services. Furthermore, when discovering services, these plugins crashed with "ValueError (item must be None or of type `str`)".