SUMMARY
Every time the screen locker activates it fails.

STEPS TO REPRODUCE
1. Lock screen manually or timed logout
2. 
3. 

OBSERVED RESULT
"The screen locker is broken and unlocking is not possible anymore."
The screen locking does work.

 
EXPECTED RESULT
Screen should be locked  but able to unlock.

SOFTWARE/OS VERSIONS
Windows: 
macOS: 
(available in the Info Center app, or by running `kinfo` in a terminal window)
Linux/KDE Plasma: plasma-workspace.x86_64 6.4.1-2.fc42
KDE Plasma Version: 6.4
KDE Frameworks Version:  kf5
Qt Version: 4.8.7

ADDITIONAL INFORMATION:

Journalctl reports 
file:///usr/share/plasma/shells/org.kde.plasma.desktop/contents/lockscreen/LockOsd.qml:10:1: "../osd": no such directory
Segmentation fault

Running "/usr/libexec/kscreenlocker_greet" generates the same problem. The directory mentioned does not exist. 
Installed packages
kscreen.x86_64                   1:6.4.1-1.fc42 updates
kscreenlocker.x86_64             6.4.1-1.fc42   updates

The directory should be provided by the package plasma-desktop but is not present. The older plasma-desktop-6.3.4-1.fc42.x86_64.rpm does have this directory.  I tried copying the directory from this  older rpm into the current location. It still did not work.