message: Check m_internals in UnregisterValidationInterface
diff: @@ -69,8 +69,10 @@ void RegisterValidationInterface(CValidationInterface* pwalletIn) {
  }
  void UnregisterValidationInterface(CValidationInterface* pwalletIn) {
  + if (g_signals.m_internals) {
  g_signals.m_internals->m_connMainSignals.erase(pwalletIn);
  }
  +}
  void UnregisterAllValidationInterfaces() {
  if (!g_signals.m_internals) {
  