Checkmk Werk 11754: LDAP: Fix connection error displaying

ID: 11754 Title: LDAP: Fix connection error displaying Component: Multisite Level: 1 Class: Bug fix Version: 2.1.0i1 Errors that may occur when trying to connect to the configured LDAP server were not displayed correctly in the GUI. Instead an error like "TypeError: 'SERVER_DOWN' object is not subscriptable" was shown.