I Think The Solution Is "Simple"
("Easy, when you know how...")
Just say MATCH errors on NULL input...but then use VETO-in-NULL-out to bypass thatn.
So if you want a NULL => NULL conflation, instead of writing this:
match [null? integer! text!] var-might-be-null
You write this:
match [integer! text!] cond var-might-be-null
