Unchecked return value

If the function returns an error value, the error value may be mistaken for a normal value. Value returned from a function is not checked for errors before being used
/src/mongo/db/s/balancer/balancer_defragmentation_policy_impl.cpp:1447: CHECKED_RETURN 121399 Calling "_refreshDefragmentationPhaseFor" without checking return value (as is done elsewhere 1 out of 2 times).