error exceptions

I'm trying to get error messages to display and I was following this
tutorial.  However, I can't seem to get any error exceptions.  In a
lua script I'm running, I have a print at the top and bottom and it's
only hitting the top one, so I'm assuming there is some error in there
I thought should raise an exception.

http://www.nuclex.org/articles/5-cxx/1-quick-introduction-to-luabind

void loadLuaFile(lua_State* state, QString fileName)
{
    QFile file(fileName);
    file.open(QIODevice::ReadOnly);
    QString lines = file.readAll();
    //std://:cout << lines.toStdString() << std::endl;
    try {
        std::cout << "executing " << fileName.toStdString() <<
"...\n-----------" << std::endl;
        std::cout << lines.toStdString().c_str() << std::endl;
        luaL_dostring(state, lines.toStdString().c_str());
    } catch (const std::exception &TheError) {
        std::cout << "*" << std::endl;
        std::cout << TheError.what() << std::endl;
    }

    file.close();
}

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