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 :-)
for (size_t posInBlock = 0; posInBlock < block.vtx.size(); ++posInBlock) {
                    SyncTransaction(block.vtx[posInBlock], pindex, posInBlock, fUpdate);
                }
            } else {
                ret = pindex;
            }
            if (pindex == pindexStop) {
                break;
            }
            {
                LOCK(cs_main);
                pindex = chainActive.Next(pindex);
                progress_current = GuessVerificationProgress(chainParams.TxData(), pindex);
                if (pindexStop == nullptr && tip != chainActive.Tip()) {
                    tip = chainActive.Tip();
                    
                    progress_end = GuessVerificationProgress(chainParams.TxData(), tip);
                }
            }
        }
        if (pindex && fAbortRescan) {
            LogPrintf("Rescan aborted at block %d. Progress=%f\n", pindex->nHeight, progress_current);
        } else if (pindex && ShutdownRequested()) {
            LogPrintf("Rescan interrupted by shutdown request at block %d. Progress=%f\n", pindex->nHeight, progress_current);
        }
        ShowProgress(_("Rescanning..."), 100); 
    }
    return ret;
}
void CWallet::ReacceptWalletTransactions()