Re: Avoid possible deference NULL pointer (src/backend/optimizer/path/allpaths.c)

But what should we do if cheapest == NULL further? Should we return NULL
of get_cheapest_parameterized_child_path() function?

If it is, we should write it like this:

if (cheapset == NULL || bms(PATH_REQ_OUTER(cheapset), required_outer))
     return cheapest;