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/bson/util/bsoncolumnbuilder.cpp:1019: NULL_FIELD 175148 Reading field "control", which is expected to possibly be "nullptr" in "this->current.control" (checked 7 out of 7 times).
/src/mongo/bson/util/bsoncolumnbuilder.cpp:1019: NULL_FIELD 175148 Assigning: "control" = "this->current.control".
/src/mongo/bson/util/bsoncolumnbuilder.cpp:1025: NULL_FIELD 175148 Dereferencing "control", which is known to be "nullptr".