1. Create a new Qt Quick Application project using the defaults from the wizard.
2. Start the QML Profiler for this application.
3. While the Profiler is recording, try to quit Creator.
   You'll see a warning, that the application is still running.
4. Click "Force Quit".
   On the command line Creator was called from you can read:

   SOFT ASSERT: "d->m_profilerState" in file /home/qtrob/dev/src/creator-4.4-enterprise/qtcreator/src/plugins/qmlprofiler/qmlprofilerruncontrol.cpp, line 144
   

In addition to the workaround, this situation should be fixed properly