fix: Protection against wrong configuration of Seed finder config (#2129

)

In case a misconfiguration of the `SeedFinderConfig`  happens, and the `seedFilter` is a nullptr, the code crashes.

This PR adds a protection against this eventuality. This happens in the `toInternalUnits` function, that now takes responsibility for checking the validity of its parameters.

It checks that the seedFilter is not a `nullptr` and that its config is already in internal units.

Core/include/Acts/Seeding/SeedFinderConfig.hpp

@@ -177,6 +177,19 @@ struct SeedFinderConfig {
       throw std::runtime_error(
           "Repeated conversion to internal units for SeedFinderConfig");
     }
+    // Make sure the shared ptr to the seed filter is not a nullptr
+    // And make sure the seed filter config is in internal units as well
+    if (not seedFilter) {
+      throw std::runtime_error(
+          "Invalid values for the seed filter inside the seed filter config: "
+          "nullptr");
+    }
+    if (not seedFilter->getSeedFilterConfig().isInInternalUnits) {
+      throw std::runtime_error(
+          "The internal Seed Filter configuration, contained in the seed "
+          "finder config, is not in internal units.");
+    }
+
     using namespace Acts::UnitLiterals;
     SeedFinderConfig config = *this;
     config.isInInternalUnits = true;

Examples/Algorithms/TrackFinding/src/SeedingAlgorithm.cpp

@@ -25,12 +25,17 @@
 ActsExamples::SeedingAlgorithm::SeedingAlgorithm(
     ActsExamples::SeedingAlgorithm::Config cfg, Acts::Logging::Level lvl)
     : ActsExamples::IAlgorithm("SeedingAlgorithm", lvl), m_cfg(std::move(cfg)) {
+  // Seed Finder config requires Seed Filter object before convertion to
+  // internal units
+  m_cfg.seedFilterConfig = m_cfg.seedFilterConfig.toInternalUnits();
+  m_cfg.seedFinderConfig.seedFilter =
+      std::make_unique<Acts::SeedFilter<SimSpacePoint>>(m_cfg.seedFilterConfig);
+
   m_cfg.seedFinderConfig =
       m_cfg.seedFinderConfig.toInternalUnits().calculateDerivedQuantities();
   m_cfg.seedFinderOptions =
       m_cfg.seedFinderOptions.toInternalUnits().calculateDerivedQuantities(
           m_cfg.seedFinderConfig);
-  m_cfg.seedFilterConfig = m_cfg.seedFilterConfig.toInternalUnits();
   m_cfg.gridConfig = m_cfg.gridConfig.toInternalUnits();
   m_cfg.gridOptions = m_cfg.gridOptions.toInternalUnits();
   if (m_cfg.inputSpacePoints.empty()) {