Make sure to not continue without any podio

CMakeLists.txt

@@ -22,11 +22,18 @@ project(k4FWCore)
 
 find_package(ROOT COMPONENTS RIO Tree REQUIRED)
 find_package(Gaudi REQUIRED)
-  find_package(podio 0.16.3)  # this will not find 1.0 and newer
-  if(NOT podio_FOUND)
-    # we try to find a newer version now
-    find_package(podio 1.0 REQUIRED)
-  endif()
+find_package(podio 0.16.3 QUIET)  # this will not find 1.0 and newer
+if(NOT podio_FOUND)
+  # we try to find a newer version now
+  find_package(podio 1.0 REQUIRED)
+else()
+  message(WARNING "Found podio < 1.0. This should still work, but consider moving to a newer version")
+endif()
+
+if(NOT podio_FOUND)
+  message(FATAL_ERROR "Could not find a suitable version of podio")
+endif()
+
 find_package(EDM4HEP REQUIRED)
 
 include(cmake/Key4hepConfig.cmake)