Ever since Frameworks got updated to 5.82, it seems trying to search files via Dolphin outside of one’s home folder causes kdedinit5 errors like inotify_add_watch(/etc/NetworkManager/system-connections) failed: (Permission denied) and QWidget: Cannot create a QWidget without QApplication, resulting in filenamesearch. to dump core. Seems to be another oopsie in KDE’s end that people are already reporting on their bug tracker.
Just so you know 
Edit: To clarify, this crash occurs with any root-only folder or file the search comes across first. So the directory can differ on each occurence.