message: array access protection
diff: @@ -902,11 +902,14 @@ void AliTPCDigitizer::DigitizeWithTailAndCrossTalk(Option_t* option) {
  TObjArray *arrTRF = (TObjArray *) timeResFunc.At(isector); /// get ion tail for sector
  if (arrTRF == nullptr) continue;
  TGraphErrors *graphTRFPRF = (TGraphErrors *) arrTRF->At(0);
  +
  if (graphTRFPRF == NULL) continue;
  + Int_t nPoints=graphTRFPRF->GetN();
  Int_t nTimes = crossTalkMatrix->GetNcols();
  for (Int_t iwire = 0; iwire < crossTalkMatrix->GetNrows(); iwire++) {
  for (Int_t itime = 0; itime < crossTalkMatrix->GetNcols(); itime++) {
  for (Int_t jtime = itime + 1; jtime < crossTalkMatrix->GetNcols(); jtime++) {
  + if (jtime - itime>=nPoints) continue;
  Double_t trf = graphTRFPRF->GetY()[jtime - itime];
  if (trf < 0) {
  matrixTail(iwire, jtime) += (*crossTalkMatrix)(iwire, itime) * trf;
  