message: check ESD track pointer - Fix Crash/Warning remained
  seems to be ESD container is not compact anymore
diff: @@ -871,6 +871,7 @@ Int_t AliESDtools::DumpEventVariables() {
  Int_t eventMult = fEvent->GetNumberOfESDTracks();
  for (Int_t iTrack=0;iTrack<eventMult;++iTrack){
  AliESDtrack *track = fEvent->GetTrack(iTrack);
  + if (track== nullptr) continue;
  if (track->IsOn(AliESDtrack::kTPCin)) TPCMult++;
  }
  