I can reproduce an issue with master; v0.17.1rc1 works fine.

Steps to reproduce:
- `bitcoin-qt -regtest`
- open Console window
- repeat `generatetoaddress 1 AN_ADDRESS` some times until crash

Crash occurs both on wayland and x11.

[debug.log](https://github.com/bitcoin/bitcoin/files/2690776/debug.log)

[wallets.zip](https://github.com/bitcoin/bitcoin/files/2690781/wallets.zip)
{
    if (!clientModel || !clientModel->getOptionsModel())
        return;
    OptionsDialog dlg(this, enableWallet);
    dlg.setCurrentTab(tab);
    dlg.setModel(clientModel->getOptionsModel());
    dlg.exec();
}
void BitcoinGUI::setNumBlocks(int count, const QDateTime& blockDate, double nVerificationProgress, bool header)
{
#ifdef Q_OS_MAC
    (m_node.isInitialBlockDownload() || m_node.getReindex() || m_node.getImporting()) ? m_app_nap_inhibitor->disableAppNap() : m_app_nap_inhibitor->enableAppNap();
#endif
    if (modalOverlay)
    {
        if (header)
            modalOverlay->setKnownBestHeight(count, blockDate);
        else
            modalOverlay->tipUpdate(count, blockDate, nVerificationProgress);
    }
    if (!clientModel)
        return;
    
    statusBar()->clearMessage();
    
    enum BlockSource blockSource = clientModel->getBlockSource();