preferred way to use PG_GETARG_BYTEA_P in SPI

I'm curious what's considered the best way to invoke PG_GETARG_BYTEA_P
in an SPI routine and properly check for null input in non 'strict'
routines.  Right now, I'm looking at PG_GETARG_POINTER to check for
null value before using PG_GETARG_BYTEA_P to assign to the bytea
pointer.

ISTM a little but unintuitive to have PG_GETARG_BYTEA_P crash on null
input...why not just assign null and skip the de-toast call in the
macro?

merlin