[KCoreDirLister] Guard uiDelegate(), it might be null
Fixes filenamesearch crashing. Looks wrong to me, though... also I recall some uiDelegate-related MR from @ahmadsamir somewhere? Anyway, fixes the crash for me :)
(I wonder why filenamsearch spits a million file not found errors as I search but that is a different story)
Edited by Kai Uwe Broulik