in desktopexecparser.cpp there's this line:
            result << QStandardPaths::findExecutable("kdesu") << "-u";

which will lead to bogus paths if kdesu can not be found but a desktop file contains X-KDE-SubstituteUID=true. kdesu lives in kde-cli-tools which is part of the workspace, so a framework very much should not depend on it or at the very least correctly handle it not being there. currently desktopexecparser will return an invalid argument list in this case leading to broken end results as the argument list at that point will no longer constitute a valid command in any form.

e.g. 
args ("", "-u", "root", "-c", "/usr/sbin/synaptic")


(alternatively kdesu perhaps should be moved into a framework)

Reproducible: Always