Birdseed
If the lights were on then you had every right to assume that ALL of the ground equipment was "behind the line".
They also had a responsibility to signal you in any manner possible if it was not.
Your professionalism was the final barrier to an allision.
So their bad was twofold.
I still see baggage handlers driving strings of full, or worse, empty igloo trailers across the apron at speeds that deny any means of prevention of damage to others and aircraft if it comes uncoupled. But nobody seems to take any notice.