If `addrProxy` or `addrSeparateProxyTor` do not have a colon in the string somewhere in the QSettings storage, then attempting to open the options dialog will cause the entire program to crash.

I'm not sure if this is really a problem since it is impossible to make those strings not have colons in them from normal operation. In order to replicate this, you must modify what QSettings stores (a conf file in Linux and Registry in Windows).
{
    qWarning() << "Backing up GUI settings to" << GUIUtil::boostPathToQString(filename);
    QSettings dst(GUIUtil::boostPathToQString(filename), QSettings::IniFormat);
    dst.clear();
    CopySettings(dst, src);
}
void OptionsModel::Reset()
{
    QSettings settings;
    
    BackupSettings(GetDataDir(true) / "guisettings.ini.bak", settings);
    
    QString dataDir = Intro::getDefaultDataDirectory();
    dataDir = settings.value("strDataDir", dataDir).toString();
    
    settings.clear();
    
    settings.setValue("strDataDir", dataDir);
    
    settings.setValue("fReset", true);
    
    if (GUIUtil::GetStartOnSystemStartup())
        GUIUtil::SetStartOnSystemStartup(false);
}
int OptionsModel::rowCount(const QModelIndex & parent) const