When launching applications through krunner, they become sub-processes of krunner. When krunner encounters a bug that makes it necessary to kill it, also these applications are killed. I think it would be better if the applications are launched in their own process, separately from krunner.
I can confirm. I think I've seen the same also with Kickoff, at least my Qt Creator sometimes just disappears when I quit plasmashell. CC'ing David Faure. Happens with both the service runner (that lists applications) which does KRun::runService(*service) as well as with the shell runner which does KRun::runCommand
*** Bug 364268 has been marked as a duplicate of this bug. ***
*** Bug 263705 has been marked as a duplicate of this bug. ***
This is fixed with the port to KIO::ApplicationLauncherJob and KIO::CommandLauncherJob in https://phabricator.kde.org/D28347.