In trying to debug #12337 I added a sleep at the end of AppInitMain() to simulate being able to close the application late in the AppInitMain() process. If I close the splash screen at this point, I get a reliable crash when the splashs screen is deleted as it tries to disconnect itself from the wallet ShowProgress signal after Shutdown() has been called and the wallet has been deleted.
try
    {
        app.createWindow(networkStyle.data());
        
        
        
        if (BitcoinCore::baseInitialize()) {
            app.requestInitialize();
#if defined(Q_OS_WIN) && QT_VERSION >= 0x050000
            WinShutdownMonitor::registerShutdownBlockReason(QObject::tr("%1 didn't yet exit safely...").arg(QObject::tr(PACKAGE_NAME)), (HWND)app.getMainWinId());
#endif
            app.exec();
            app.requestShutdown();
            app.exec();
            rv = app.getReturnValue();
        } else {
            
            rv = EXIT_FAILURE;
        }
    } catch (const std::exception& e) {
        PrintExceptionContinue(&e, "Runaway exception");
        app.handleRunawayException(QString::fromStdString(GetWarnings("gui")));
    } catch (...) {
        PrintExceptionContinue(nullptr, "Runaway exception");
        app.handleRunawayException(QString::fromStdString(GetWarnings("gui")));
    }
    return rv;
}
#endif