[PWGHF] taskOmegac0ToOmegapi: Fix bug introduced in #11881 (#11979)

Author: fcatalan92

PWGHF/D2H/Tasks/taskOmegac0ToOmegapi.cxx

@@ -121,13 +121,17 @@ struct HfTaskOmegac0ToOmegapi {
   void init(InitContext&)
   {
     std::array<bool, 6> doprocess{doprocessDataWithKFParticle, doprocessDataWithKFParticleMl, doprocessDataWithKFParticleFT0C, doprocessDataWithKFParticleMlFT0C, doprocessDataWithKFParticleFT0M, doprocessDataWithKFParticleMlFT0M};
-    if ((std::accumulate(doprocess.begin(), doprocess.end(), 0)) != 1) {
-      LOGP(fatal, "One and only one data process function should be enabled at a time.");
+    if (std::accumulate(doprocess.begin(), doprocess.end(), 0) > 1) {
+      LOGP(fatal, "At most one data process function should be enabled at a time.");
     }
 
     std::array<bool, 2> doprocessMc{doprocessMcWithKFParticle, doprocessMcWithKFParticleMl};
-    if ((std::accumulate(doprocessMc.begin(), doprocessMc.end(), 0)) != 1) {
-      LOGP(fatal, "One and only one MC process function should be enabled at a time.");
+    if (std::accumulate(doprocessMc.begin(), doprocessMc.end(), 0) > 1) {
+      LOGP(fatal, "At most one MC process function should be enabled at a time.");
+    }
+
+    if ((std::accumulate(doprocess.begin(), doprocess.end(), 0) + std::accumulate(doprocessMc.begin(), doprocessMc.end(), 0)) == 0) {
+      LOGP(fatal, "At least one process function should be enabled.");
     }
 
     const AxisSpec thnAxisMass{thnConfigAxisMass, "inv. mass (#Omega#pi) (GeV/#it{c}^{2})"};