Don't crash on incorrect +grab product type in marks.
Don't crash on incorrect +grab product type in marks.

joemfb/arvo,ngzax/urbit,ngzax/urbit,ngzax/urbit,urbit/urbit,urbit/urbit,jfranklin9000/urbit,urbit/urbit,jfranklin9000/urbit,ngzax/urbit,ngzax/urbit,urbit/urbit,urbit/urbit,joemfb/arvo,belisarius222/arvo,ngzax/urbit,belisarius222/arvo,jfranklin9000/urbit,ngzax/urbit,jfranklin9000/urbit,jfranklin9000/urbit,jfranklin9000/urbit,urbit/urbit,urbit/urbit,jfranklin9000/urbit