Invalid characters for a wallet name, e.g. `bitcoin-qt -wallet=你好` used to result in an error like this

<img width="494" alt="schermafbeelding 2018-07-24 om 17 46 37" src="https://user-images.githubusercontent.com/10217/43150553-7bdf598a-8f6a-11e8-8972-44c311a57e56.png">

But now it just crashes:

<img width="509" alt="schermafbeelding 2018-07-24 om 17 43 26" src="https://user-images.githubusercontent.com/10217/43150605-9cf32192-8f6a-11e8-9333-87d074c8dd35.png">

I didn't do a `git bisect`, but it broke somewhere this year :-)
{
    return !hdChain.seed_id.IsNull();
}
void CWallet::SetWalletFlag(uint64_t flags)
{
    LOCK(cs_wallet);
    m_wallet_flags |= flags;
    if (!WalletBatch(*database).WriteWalletFlags(m_wallet_flags))
        throw std::runtime_error(std::string(__func__) + ": writing wallet flags failed");
}
bool CWallet::IsWalletFlagSet(uint64_t flag)
{
    return (m_wallet_flags & flag);
}
bool CWallet::SetWalletFlags(uint64_t overwriteFlags, bool memonly)
{
    LOCK(cs_wallet);
    m_wallet_flags = overwriteFlags;
    if (((overwriteFlags & g_known_wallet_flags) >> 32) ^ (overwriteFlags >> 32)) {
        
        return false;
    }
    if (!memonly && !WalletBatch(*database).WriteWalletFlags(m_wallet_flags)) {
        throw std::runtime_error(std::string(__func__) + ": writing wallet flags failed");
    }
    return true;
}
int64_t CWalletTx::GetTxTime() const