When a block instance component has an empty transformation input, a block instance is placed at the world origin. With a stream filter it can happen that an input is empty and in this case I would prefer a Null output.
Thanks for the report. I can get that on the list as RH-99961. An empty transformation input should give a null output, not an instance at the world origin.
RH-99961 is fixed in Rhino 8 Service Release 38 Release Candidate