DPL Analysis: do not override error-handler reader for MC injected workflows

Author: aalkin

Framework/Core/src/ArrowSupport.cxx

@@ -684,8 +684,10 @@ o2::framework::ServiceSpec ArrowSupport::arrowBackendSpec()
           workflow.erase(reader);
         } else {
           // load reader algorithm before deployment
-          auto&& algo = PluginManager::loadAlgorithmFromPlugin("O2FrameworkAnalysisSupport", "ROOTFileReader", ctx);
-          reader->algorithm = CommonDataProcessors::wrapWithTimesliceConsumption(algo);
+          auto mctracks2aod = std::find_if(workflow.begin(), workflow.end(), [](auto const& x) { return x.name == "mctracks-to-aod"; });
+          if (mctracks2aod == workflow.end()) { // add normal reader algorithm only if no on-the-fly generator is injected
+            reader->algorithm = CommonDataProcessors::wrapWithTimesliceConsumption(PluginManager::loadAlgorithmFromPlugin("O2FrameworkAnalysisSupport", "ROOTFileReader", ctx));
+          } // otherwise the algorithm was set in injectServiceDevices
         }
       }