Checkmk Werk 12737: Fix internal error while sorting by ip address in views

ID: 12737 Title: Fix internal error while sorting by ip address in views Component: Multisite Level: 1 Class: Bug fix Version: 2.1.0i1 When sorting by ip address in views, an internal error "'>' not supported between instances of 'tuple' and 'str'" occurred, if there were hosts in the shown table that have no ip address set.