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/exec/sbe/stages/fetch.cpp:271: NULL_FIELD 183646 Reading field "_cursor", which is expected to possibly be "nullptr" in "this->_cursor" (checked 4 out of 5 times).
/src/mongo/db/exec/sbe/stages/fetch.cpp:271: NULL_FIELD 183646 Attempting to access the managed object of an empty smart pointer "this->_cursor".