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)
{
    switch(status)
    {
    case WalletModel::Unencrypted:
        labelWalletEncryptionIcon->hide();
        encryptWalletAction->setChecked(false);
        changePassphraseAction->setEnabled(false);
        encryptWalletAction->setEnabled(true);
        break;
    case WalletModel::Unlocked:
        labelWalletEncryptionIcon->show();
        labelWalletEncryptionIcon->setPixmap(platformStyle->SingleColorIcon(":/icons/lock_open").pixmap(STATUSBAR_ICONSIZE,STATUSBAR_ICONSIZE));
        labelWalletEncryptionIcon->setToolTip(tr("Wallet is <b>encrypted</b> and currently <b>unlocked</b>"));
        encryptWalletAction->setChecked(true);
        changePassphraseAction->setEnabled(true);
        encryptWalletAction->setEnabled(false); 
        break;
    case WalletModel::Locked:
        labelWalletEncryptionIcon->show();
        labelWalletEncryptionIcon->setPixmap(platformStyle->SingleColorIcon(":/icons/lock_closed").pixmap(STATUSBAR_ICONSIZE,STATUSBAR_ICONSIZE));
        labelWalletEncryptionIcon->setToolTip(tr("Wallet is <b>encrypted</b> and currently <b>locked</b>"));
        encryptWalletAction->setChecked(true);
        changePassphraseAction->setEnabled(true);
        encryptWalletAction->setEnabled(false); 
        break;
    }
}
void BitcoinGUI::updateWalletStatus()