message: Minor bug fix for NanoAODs
  o For NanoAODs we don't have the matching Photon <-> v0
diff: @@ -219,8 +219,6 @@ void AliSigma0PhotonCuts::PhotonCuts(
  continue;
  AliAODv0 *v0 = inputEvent->GetV0(PhotonCandidate->GetV0Index());
  - if (!v0)
  - continue;
  fHistCuts->Fill(1.f);
  auto pos = GetTrack(dynamic_cast<AliVEvent*>(inputEvent),
  @@ -231,6 +229,9 @@ void AliSigma0PhotonCuts::PhotonCuts(
  continue;
  fHistCuts->Fill(2.f);
  + auto nanoPos = dynamic_cast<AliNanoAODTrack *>(pos);
  + if(nanoPos) v0 = nullptr; // for NanoAODs we dont have a v0 matching!
  +
  if (ProcessPhoton(event, PhotonCandidate, v0, pos, neg)) {
  container.push_back( { PhotonCandidate, pos, neg, inputEvent });
  }
  @@ -295,13 +296,13 @@ bool AliSigma0PhotonCuts::ProcessPhoton(AliVEvent* event,
  const float phi = PhotonCandidate->GetPhotonPhi();
  const float psiPair = PhotonCandidate->GetPsiPair();
  - const float dcaV0Daughters = v0->DcaV0Daughters();
  + const float dcaV0Daughters = (v0) ? v0->DcaV0Daughters() : 0;
  const float posPt = pos->Pt();
  const float negPt = neg->Pt();
  const float posEta = pos->Eta();
  const float negEta = neg->Eta();
  - const float dcaDaughterToPVPos = v0->DcaPosToPrimVertex();
  + const float dcaDaughterToPVPos = (v0) ? v0->DcaPosToPrimVertex() : 0;
  const short nClsTPCPos = pos->GetTPCNcls();
  const float nCrossedRowsPos =
  (nanoPos) ? nanoPos->GetTPCNCrossedRows() : pos->GetTPCClusterInfo(2, 1);
  @@ -312,7 +313,7 @@ bool AliSigma0PhotonCuts::ProcessPhoton(AliVEvent* event,
  (nClsTPCPos > 5) ? (pos->GetTPCchi2() / float(nClsTPCPos - 5)) : -1.;
  if(nanoPos) chi2Pos = nanoPos->Chi2perNDF();
  - const float dcaDaughterToPVNeg = v0->DcaNegToPrimVertex();
  + const float dcaDaughterToPVNeg = (v0) ? v0->DcaNegToPrimVertex() : 0;
  const short nClsTPCNeg = neg->GetTPCNcls();
  const float nCrossedRowsNeg =
  (nanoNeg) ? nanoNeg->GetTPCNCrossedRows() : neg->GetTPCClusterInfo(2, 1);
  