message: log CWallet::MintToTxIn errors
diff: @@ -4680,7 +4680,7 @@ bool CWallet::MintToTxIn(CZerocoinMint zerocoinSelected, int nSecurityLevel, con
  //LogPrintf("%s : selected mint %s\n pubcoinhash=%s\n", __func__, zerocoinSelected.ToString(), GetPubCoinHash(zerocoinSelected.GetValue()).GetHex());
  if (!pubCoinSelected.validate()) {
  receipt.SetStatus(_("The selected mint coin is an invalid coin"), ZPIV_INVALID_COIN);
  - return false;
  + return error("%s : %s", __func__, receipt.GetStatusMessage());
  }
  // 3. Compute Accumulator and Witness
  @@ -4730,7 +4730,7 @@ bool CWallet::MintToTxIn(CZerocoinMint zerocoinSelected, int nSecurityLevel, con
  libzerocoin::CoinSpend spend2(Params().Zerocoin_Params(true), paramsAccumulator, privateCoin, accumulator,
  nChecksum, witness, hashTxOut, libzerocoin::SpendType::SPEND);
  LogPrintf("*** spend2 valid=%d\n", spend2.Verify(accumulator));
  - return false;
  + return error("%s : %s", __func__, receipt.GetStatusMessage());
  }
  // Deserialize the CoinSpend intro a fresh object
  @@ -4753,13 +4753,13 @@ bool CWallet::MintToTxIn(CZerocoinMint zerocoinSelected, int nSecurityLevel, con
  serializedCoinSpendChecking << spend;
  } catch (...) {
  receipt.SetStatus(_("Failed to deserialize"), ZPIV_BAD_SERIALIZATION);
  - return false;
  + return error("%s : %s", __func__, receipt.GetStatusMessage());
  }
  libzerocoin::CoinSpend newSpendChecking(paramsCoin, paramsAccumulator, serializedCoinSpendChecking);
  if (!newSpendChecking.Verify(accumulator)) {
  receipt.SetStatus(_("The transaction did not verify"), ZPIV_BAD_SERIALIZATION);
  - return false;
  + return error("%s : %s", __func__, receipt.GetStatusMessage());
  }
  if (IsSerialKnown(spend.getCoinSerialNumber())) {
  @@ -4776,7 +4776,7 @@ bool CWallet::MintToTxIn(CZerocoinMint zerocoinSelected, int nSecurityLevel, con
  LogPrintf("%s: failed to write zerocoinmint\n", __func__);
  pwalletMain->NotifyZerocoinChanged(pwalletMain, zerocoinSelected.GetValue().GetHex(), "Used", CT_UPDATED);
  - return false;
  + return error("%s : %s", __func__, receipt.GetStatusMessage());
  }
  uint32_t nAccumulatorChecksum = GetChecksum(accumulator.getValue());
  @@ -4785,7 +4785,7 @@ bool CWallet::MintToTxIn(CZerocoinMint zerocoinSelected, int nSecurityLevel, con
  receipt.AddSpend(zcSpend);
  } catch (const std::exception&) {
  receipt.SetStatus(_("CoinSpend: Accumulator witness does not verify"), ZPIV_INVALID_WITNESS);
  - return false;
  + return error("%s : %s", __func__, receipt.GetStatusMessage());
  }
  receipt.SetStatus(_("Spend Valid"), ZPIV_SPEND_OKAY); // Everything okay
  