From 006ea3685f2c47e2b467e175b4a0b31e4c022ac6 Mon Sep 17 00:00:00 2001
From: Maximiliano Puccio <maximiliano.puccio@cern.ch>
Date: Tue, 12 Sep 2023 14:44:46 +0200
Subject: [PATCH] Avoid crash with no collisions

---
 PWGLF/TableProducer/lambdakzerobuilder.cxx | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/PWGLF/TableProducer/lambdakzerobuilder.cxx b/PWGLF/TableProducer/lambdakzerobuilder.cxx
index 62f6007770d..15e1a0fffa2 100644
--- a/PWGLF/TableProducer/lambdakzerobuilder.cxx
+++ b/PWGLF/TableProducer/lambdakzerobuilder.cxx
@@ -732,11 +732,14 @@ struct lambdakzeroBuilder {
   }
   PROCESS_SWITCH(lambdakzeroBuilder, processRun2, "Produce Run 2 V0 tables", false);
 
-  void processRun3(aod::Collisions const& collisions, soa::Filtered<TaggedV0s> const& V0s, FullTracksExtIU const&, aod::BCsWithTimestamps const&)
+  void processRun3(aod::Collisions const& collisions, soa::Filtered<TaggedV0s> const& V0s, FullTracksExtIU const&, aod::BCsWithTimestamps const& bcs)
   {
     // Fire up CCDB
-    auto collision = collisions.begin();
-    auto bc = collision.bc_as<aod::BCsWithTimestamps>();
+    auto bc = collisions.size() ? collisions.begin().bc_as<aod::BCsWithTimestamps>() : bcs.begin();
+    if (!bcs.size()) {
+      LOGF(warn, "No BC found, skipping this DF.");
+      return;
+    }
     initCCDB(bc);
     buildStrangenessTables<FullTracksExtIU>(V0s);
   }