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 (!walletFrame) {
        return;
    }
    WalletView * const walletView = walletFrame->currentWalletView();
    if (!walletView) {
        return;
    }
    WalletModel * const walletModel = walletView->getWalletModel();
    setEncryptionStatus(walletModel->getEncryptionStatus());
    setHDStatus(walletModel->privateKeysDisabled(), walletModel->wallet().hdEnabled());
}
#endif 
void BitcoinGUI::updateProxyIcon()
{
    std::string ip_port;
    bool proxy_enabled = clientModel->getProxyInfo(ip_port);
    if (proxy_enabled) {
        if (labelProxyIcon->pixmap() == 0) {
            QString ip_port_q = QString::fromStdString(ip_port);
            labelProxyIcon->setPixmap(platformStyle->SingleColorIcon(":/icons/proxy").pixmap(STATUSBAR_ICONSIZE, STATUSBAR_ICONSIZE));
            labelProxyIcon->setToolTip(tr("Proxy is <b>enabled</b>: %1").arg(ip_port_q));
        } else {
            labelProxyIcon->show();
        }
    } else {
        labelProxyIcon->hide();
    }
}
void BitcoinGUI::showNormalIfMinimized(bool fToggleHidden)