Running test case B1Con run1.mac I get zero divided by zero at G4ConvergenceTester.cc:156 because variables vov and var are zero.
Thank you for reporting problem. I add protections to avoid core dumps caused by divided by zero in G4ConvergenceTester. Now G4convergenceTester becomes much robust than before. I also increase number of events of run1.mac to fit the purpose of B1Con example.