spatial: difference in st_box2dfromgeohash result

[rafiss]

Running on Postgis:

postgres=# select st_box2dfromgeohash('F'::TEXT::TEXT::TEXT, NULL::INT4::INT4)::BOX2D ;
 st_box2dfromgeohash
---------------------
 BOX(-90 45,-45 90)

But on CockroachDB:

root@:26257/defaultdb> select st_box2dfromgeohash('F'::TEXT::TEXT::TEXT, NULL::INT4::INT4)::BOX2D ;
  st_box2dfromgeohash
-----------------------
  NULL

[mgartner]

Setting NullableArgs: true for this builtin will prevent it from being folded to NULL in the presence of null arguments. We'll need to make sure the function can actually handle either argument being NULL.

Also, it looks like the single-argument overload of this function errors with the same input, when it succeeds in Postgis:

Postgis:

marcus=# select st_box2dfromgeohash('F'::TEXT::TEXT::TEXT)::BOX2D;
 st_box2dfromgeohash
---------------------
 BOX(-90 45,-45 90)

CockroachDB:

defaultdb> select st_box2dfromgeohash('F'::TEXT::TEXT::TEXT)::BOX2D;
ERROR: st_box2dfromgeohash(): geohash decode 'F': invalid character at index 0