message: Guard against non-integer input for GUI's custombackupthreshold
diff: #include "rpcclient.h"
  #include "rpcserver.h"
  #include "util.h"
  +#ifdef ENABLE_WALLET
  +#include "wallet.h"
  +#endif // ENABLE_WALLET
  #include <openssl/crypto.h>
  @@ -291,7 +294,7 @@ RPCConsole::RPCConsole(QWidget* parent) : QDialog(parent),
  #ifdef ENABLE_WALLET
  std::string strPathCustom = GetArg("-backuppath", "");
  std::string strzPIVPathCustom = GetArg("-zpivbackuppath", "");
  - std::string strCustomBackupThreshold = GetArg("-custombackupthreshold", "");
  + int nCustomBackupThreshold = GetArg("-custombackupthreshold", DEFAULT_CUSTOMBACKUPTHRESHOLD);
  if(!strPathCustom.empty()) {
  ui->wallet_custombackuppath->setText(QString::fromStdString(strPathCustom));
  @@ -305,8 +308,8 @@ RPCConsole::RPCConsole(QWidget* parent) : QDialog(parent),
  ui->wallet_customzpivbackuppath->setVisible(true);
  }
  - if(!strCustomBackupThreshold.empty()) {
  - ui->wallet_custombackupthreshold->setText(QString::fromStdString(strCustomBackupThreshold));
  + if((!strPathCustom.empty() || !strzPIVPathCustom.empty()) && nCustomBackupThreshold > 0) {
  + ui->wallet_custombackupthreshold->setText(QString::fromStdString(std::to_string(nCustomBackupThreshold)));
  ui->wallet_custombackupthreshold_label->setVisible(true);
  ui->wallet_custombackupthreshold->setVisible(true);
  }
  