message: wallet: Set encrypted_batch to nullptr after delete. Avoid double free in the case of NDEBUG.
diff: @@ -687,6 +687,7 @@ bool CWallet::EncryptWallet(const SecureString& strWalletPassphrase)
  {
  encrypted_batch->TxnAbort();
  delete encrypted_batch;
  + encrypted_batch = nullptr;
  // We now probably have half of our keys encrypted in memory, and half not...
  // die and let the user reload the unencrypted wallet.
  assert(false);
  @@ -697,6 +698,7 @@ bool CWallet::EncryptWallet(const SecureString& strWalletPassphrase)
  if (!encrypted_batch->TxnCommit()) {
  delete encrypted_batch;
  + encrypted_batch = nullptr;
  // We now have keys encrypted in memory, but not on disk...
  // die to avoid confusion and let the user reload the unencrypted wallet.
  assert(false);
  