Dereference of potentially null field

If the field is actually null, then a null pointer dereference will occur. Field, which is statistically checked against null, is dereferenced.
/src/mongo/db/query/compiler/stats/rand_utils.cpp:228: NULL_FIELD 176055 Reading field "_nestedDataDescriptor", which is expected to possibly be "nullptr" in "this->_nestedDataDescriptor" (checked 4 out of 5 times).
/src/mongo/db/query/compiler/stats/rand_utils.cpp:228: NULL_FIELD 176055 Attempting to access the managed object of an empty smart pointer "this->_nestedDataDescriptor".