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/repl/tenant_migration_recipient_service.cpp:1397: NULL_FIELD 175117 Reading field "_donorOplogBuffer", which is expected to possibly be "nullptr" in "this->_donorOplogBuffer" (checked 1 out of 1 times).
/src/mongo/db/repl/tenant_migration_recipient_service.cpp:1403: NULL_FIELD 175117 Attempting to access the managed object of an empty smart pointer "donorOplogBuffer".