message: Fix: invalid iterator after erase
diff: @@ -4629,7 +4629,7 @@ bool CWallet::ListAvailableAnonOutputs(std::list<COwnedAnonOutput>& lAvailableAn
  int64_t nLastCoinValue = -1;
  int nMaxSpendable = -1;
  int nAvailableMixins = 0;
  - for (std::list<COwnedAnonOutput>::iterator it = lAvailableAnonOutputs.begin(); it != lAvailableAnonOutputs.end(); ++it)
  + for (std::list<COwnedAnonOutput>::iterator it = lAvailableAnonOutputs.begin(); it != lAvailableAnonOutputs.end();)
  {
  if (nLastCoinValue != it->nValue)
  {
  @@ -4650,11 +4650,12 @@ bool CWallet::ListAvailableAnonOutputs(std::list<COwnedAnonOutput>& lAvailableAn
  (nMaxSpendable != -1 && nCoinsPerValue >= nMaxSpendable) ||
  nAmountCheck + it->nValue > nMaxAmount)
  // -- not enough coins of same value, unspends or over max amount, drop coin
  - lAvailableAnonOutputs.erase(it);
  + it = lAvailableAnonOutputs.erase(it);
  else
  {
  nAmountCheck += it->nValue;
  nCoinsPerValue++;
  + ++it;
  }
  }
  