"Open System Monitor" in System Monitor applet fails

[Jonathan Ryshpan]

Right clicking applet "System monitor Sensor" -> "Open System
Monitor"
does nothing except bring up this message:
   Plasma Desktop Workspace
   
   Plasma Workspace
   Internal error: could not prompt the
   user for which application to start.

I would like this to start ksysguard.

System info:
   Operating System: Fedora 34
   KDE Plasma Version: 5.22.4
   KDE Frameworks Version: 5.83.0
   Qt Version: 5.15.2
   Kernel Version: 5.13.5-200.fc34.x86_64 (64-bit)
   Graphics Platform: X11
   Processors: 8 × Intel® Core™ i7-4790K CPU @ 4.00GHz
   Memory: 15.5 GiB of RAM
   Graphics Processor: Mesa DRI Intel® HD Graphics 4600
   
   System monitor Sensor 1.0

-- 
Sincerely Jonathan Ryshpan <jonrysh(a)pacbell.net&gt;

 And God fulfills himself in many ways
 Lest one good custom should corrupt the world.
 -- Tennyson