message: Added check on the branch existance
  Avoid any branch name that is not in any of the Trees
diff: @@ -201,7 +201,8 @@ void AliAnalysisTaskAO2Dconverter::Prune()
  if (fPruneList.IsNull() || fPruneList.IsWhitespace())
  return;
  TObjArray* arr = fPruneList.Tokenize(" ");
  - for (Int_t i = 0; i < arr->GetEntries(); i++)
  + for (Int_t i = 0; i < arr->GetEntries(); i++) {
  + Bool_t found = kFALSE;
  for (Int_t j = 0; j < kTrees; j++) {
  TObjArray* branches = fTree[j]->GetListOfBranches();
  for (Int_t k = 0; k < branches->GetEntries(); k++) {
  @@ -209,8 +210,12 @@ void AliAnalysisTaskAO2Dconverter::Prune()
  if (!bname.EqualTo(arr->At(i)->GetName()))
  continue;
  fTree[j]->SetBranchStatus(bname, 0);
  + found = kTRUE;
  }
  }
  + if (!found)
  + AliFatal(Form("Did not find Branch %s", arr->At(i)->GetName()));
  + }
  fPruneList = "";
  }
  