Division or modulo by float zero

This could cause an immediate crash or incorrect computation. An expression which may be zero is used as a divisor in floating-point arithmetic.
/src/mongo/db/storage/flow_control.cpp:365: DIVIDE_BY_ZERO 115732 Checking "mongo::<unnamed>::getLagMillis(myLastApplied.wallTime, lastCommitted.wallTime) < thresholdLagMillis" implies that "thresholdLagMillis" may be up to 0 on the false branch.