MICEDetectorConstruction.cc pStepper always NULL before trying to find stepping type
in 348, pStepper is set to NULL. However, a few lines later at 368 the value of pStepper is checked if it is null in an If then there is a long long list of elses that can never be seen. The whole 'if' statement in the first place doesn't do anything.
Suggestion: delete all the else's until we need them since I think they are dead relics of G4MICE (or we can always bring them back).