message: Add protection for pointer to vertex (Cristina)
diff: @@ -284,7 +284,7 @@ void AliAnalysisTrackingUncertaintiesAOT::UserExec(Option_t *)
  if (IsVertexAccepted(fESD)) {
  histVertexSelection->Fill(fVertex->GetZ(), 0);
  } else {
  - histVertexSelection->Fill(fVertex->GetZ(), 1);
  + if(fVertex) histVertexSelection->Fill(fVertex->GetZ(), 1);
  PostData(1, fListHist);
  return;
  }
  