It's not Qt specifically.
OpenCV is throwing an error in your use of fileStorage, either file doens't exist, isn't readable, or you are trying to read the wrong types.
Qt gives you that error because the exception has reached it's general error handler for an unchecked exception rather than openCv, which would print a more useful error.
You can add a global excpetion handler to a Qt app by adding a method to QApplication
bool QApplication::notify ( QObject * receiver, QEvent * event )
{
try{
return QApplication::notify( received, event );
}
catch ( const std::exception &e )
{
QApplication::postEvent( this, new MyEvent( e.what() );
}
catch ( ... )
{
}
See also http://qt-project.org/doc/qt-4.8/exceptionsafety.html