Comment 6 for bug 1672024

It's this one:

static MirWaitHandle* mir_window_request_persistent_id_helper(
    MirWindow* window, MirWindowIdCallback callback, void* context)
{
    mir::require(mir_window_is_valid(window));

    try
    {
        return window->request_persistent_id(callback, context);
    }
    catch (std::exception const& ex)
    {
        MIR_LOG_UNCAUGHT_EXCEPTION(ex);
        return nullptr;
    }
}